Herb. Cirsium arvense is an herbaceous perennial in the aster family . It occurs in nearly every upland herbaceous community within its range , and is a particular threat in grassland communities and riparian habitats . C. arvense is shade intolerant and can tolerate soils with up to 2% salt content . It grows on all but waterlogged, poorly aerated soils, including clay , clay loam, silt loam , sandy loam, sandy clay, sand dunes, gravel , limestone, and chalk , but not peat. It spreads primarily by vegetative means, and secondarily by seed. The seeds spread as a contaminant in agricultural seeds in hay and in cattle and horse droppings and on farm machinery. It produces an abundance of bristly-plumed seeds that are easily dispersed by the wind and they may also be transported by water. Nuzzo (1997) reports that American Indians purportedly used an infusion of C. arvense roots for mouth diseases. The Chippewa considered it to be a "tonic, diuretic, and astringent". Young shoots and roots "can be used in the same ways as asparagus," and were eaten in Russia and by Native Americans. The nectar of its flowers is also said to make good honey. Zouhar (2001) reports that the weed has been used by native people in the northeastern United States in remedies for worms and poison-ivy (Toxicodendron radicans) and was used to make a mouthwash for children, a treatment for tuberculosis, and a tonic for gastrointestinal ailments.
- Cirsium arvense is one of the most economically important agricultural weeds in the world. It was introduced to North America in the 1600s and soon was recognized as a problem weed. Weed control legislation against the species was passed by the Vermont legislature in 1795 (R. J. Moore 1975). Canada thistle is now listed as a noxious weed in most areas where it occurs. It has very high seed production , and the runner roots readily survive the fragmentation that accompanies cultivation. [source]
- Honeybees and bumblebees get a lot of bang for their buck on thistles. Being a composite flower, there are hundreds of tiny florets per plant, each one containing a nectar reward.
- Canada thistle was introduced to the United States, probably by accident, in the early 1600s and, by 1954, had been declared a noxious weed in forty three states. In Canada and the U.S., it is considered one of the most tenacious and economically important agricultural weeds, but only in recent years has it been recognized as a problem in natural areas.
Click on the language to view common names.
Common Names in English:
Californian Thistle, California Thistle, Canada Thistle, Canadian Thistle, Corn Thistle, Creeping Thistle, Field Thistle, Perennial Thistle
Common Names in French:
Chardon Des Champs, Chardon Du Canada, Cirse Des Champs
Common Names in Portuguese:
, biennials, or perennials
, 5-400 cm, spiny
. Stems (1-several) erect
, branched or simple
, sometimes narrowly spiny-winged. Leaves basal and cauline; finely bristly-dentate to coarsely dentate
or 1-3 times pinnately lobed
, teeth and lobes
green and glabrous
or densely gray-canescent, usually eglandular
. Heads discoid
, borne singly, terminal
and in distal axils, or in racemiform
, or corymbiform
arrays. ( Peduncles with ± reduced leaflike bracts.) Involucres cylindric
or spheric, (1-6 Ã—) 1-8 cm. Phyllaries many in 5-20 series, subequal
or weakly to strongly, outer and middle
and apices spreading
to erect, usually spine-tipped, innermost usually with erect, flat, often twisted, entire or dentate, usually spineless apices (distal portion of phyllary
in many species with elongate
, usually milky
in fresh material
but dark brown to black when dry) . Receptacles flat to convex
, epaleate, covered with tawny
to white bristles
. Florets 25-200+; corollas white to pink, red, yellow or purple, ± bilateral
long, slender, distally bent, throats
short, abruptly expanded. cylindric, lobes linear
bases sharply short-tailed, apical appendages
linear-oblong; style tips
elongate (as measured in descriptions
including the slightly swollen nodes, long cylindric fused portions of style branches and very short distinct portions) . Cypselae ovoid, ± compressed
, with apical rims, smooth
, not ribbed
, glabrous, basal attachment scars
; pappi persistent
or falling in rings
, in 3-5 series of many flattened, plumose
bristles or plumose, setiform scales (longer
bristles shorter than corollas except in C. foliosum and C.
arvense) . x = 17.
Species ca. 200: North America, Eurasia , n Africa.
Only three genera in Cynareae are represented by native species in the New World, and of these Cirsium is by far the most widely distributed and diverse . Native species of Cirsium range from sea level to alpine and from boreal regions of Canada to the tropics of Central America. Members of the genus occur in a myriad of habitats including swamps , meadows, forests , prairies, sand dunes, and deserts.
Preliminary molecular phylogenetic studies by D. G. Kelch and B . G. Baldwin (2003) indicated that this diversity is the product of a rapid evolutionary diversification based upon a single initial introduction from Eurasia. Relationships among the North American species are apparently complex , and molecular studies have only begun to provide an outline of phylogeny for these plants . Although there has been a remarkable evolutionary and morphologic diversification in North American Cirsium, it has not been accompanied by very much divergence in the base sequences of genes commonly used to elucidate phylogenetic relationships. This suggests either that the diversification has been very rapid or that genetic markers in North American Cirsium mutate more slowly than in most other lineages .
Chromosomal diversification has accompanied the morphologic radiation of North American Cirsium. Many New World Cirsium species share the chromosomal base number of x = 17 that also predominates in most Eurasian species. Among the North American thistles, however, is a mostly descending dysploid series with chromosome numbers ranging from n = 18 to n = 10. Very few instances of polyploidy are known among New World Cirsium.
Cirsium species of remarkably different morphologies often are able to hybridize . Although in some hybrid combinations fertility is reduced, in others the formation of complex hybrid swarms indicates a lack of breeding barriers and the potential for emergence of novel character combinations. In the absence of adequate sampling and field observations, hybrids may go unrecognized, treated as distinct taxa or as variants of non-hybrid taxa, or left occupying the indeterminate folders of herbaria. In other cases hybridization has been invoked without much evidence as an explanation for Cirsium variants encountered in herbaria or in the field. Hybrid combinations are listed herein when evidence is convincing. Additional hybrids are likely to be found where the ranges of Cirsium species overlap. I have seen no documentation of hybridization between native American Cirsium species and introduced Eurasian taxa.
Much of the geographic range currently occupied by New World Cirsium species was greatly affected by the events of the Quaternary . Large areas were glaciated and other areas were vastly different during glacial episodes. The ancestors of thistles that currently occupy the high mountains of western North America were undoubtedly displaced elevationally and/or latitudinally during the recurrent glacial and interglacial episodes of the Pleistocene . Taxa that are currently isolated may have been in contact during glacial episodes with the opportunity for hybridization and genetic interchange. Episodes of prehistoric hybridization may have led to some of the character combinations found in modern American thistles, particularly in the western half of the continent. Current isolation and localized selection or genetic drift apparently have promoted differentiation of populations separated on mountaintop islands.
One of the most challenging aspects for a taxonomist studying New World Cirsium is the presence of species complexes that are apparently evolutionary works in progress. Some of the thistles, especially in the mountainous western part of North America, are frustratingly polymorphic with much overlapping variability and intergradation of characters. Early taxonomists, basing their work on a limited sampling of the morphologic diversity, named many of the forms as species, and the literature is rife with species names . The infilling that results from more collectors visiting more localities within the ranges of these complexes has blurred the boundaries between many of the proposed species and often added forms that do not "fit" the characteristics of named species. As I faced the challenges of preparing this treatment, I recognized that maintaining some of the named entities as species would, for consistency, require a further proliferation of species names. I have chosen to go the other way. Instead of proposing yet more ill-defined microspecies, I have chosen to recognize that the groups in question are rapidly evolving, only partially differentiated assemblages of races that have not reached the level of stability that is usually associated with the concept of species. Certainly much of such variation within the genus deserves a level of taxonomic recognition, or at least should be mentioned, but for those assemblages I think it much more prudent to recognize varieties -- entities that may be expected to freely intergrade -- rather than species.
Many problems remain to be worked out in North American Cirsium. Further investigation will undoubtedly reveal the need for refinement or major revision within some of the species groups. Studies that focus on variation within and among populations and on the biological basis for the variations are much needed. The field is open and the challenges are many.
Preparation of a workable key to Cirsium species has been frustratingly difficult. Extensive and overlapping ranges of variation in morphologic characteristics often require that a species be keyed two or more times. The resulting key is longer and more complex than I would prefer, and I have no doubt ignored, overlooked, or been completely unaware of variants that will not key out. Caveat clavitor!
The reputation of Cirsium has suffered greatly as a result of the introduction to North America of a few invasive weedy species from Eurasia. Cirsium vulgare (bull thistle) and C. arvense (Canada thistle€”a misnomer) have long been despised as noxious weeds . In recent years C. palustre (European swamp thistle) has joined their ranks . Additionally, weedy Eurasian species of Carduus, Onopordum, Centaurea, etc. , add to the public perception that all thistles are bad. Most North American native Cirsium are not at all weedy, and many are strikingly attractive plants. All are spiny plants that command respect, but they deserve a better reputation as one of North America€™s evolutionary success stories.
Native Cirsium species have come under threat from biocontrol programs instituted to suppress populations of weedy introduced thistles. Beginning in 1968 the seedhead weevil Rhinocyllus conicus has been widely introduced in various areas of the United States and Canada, primarily to control weedy species of Carduus. S. M. Louda et al. (1997) reported that R. conicus has crossed over to several native species of Cirsium. They observed that the number of viable cypselae in infested heads was greatly reduced; e.g. , heads of C. canescens infested by R. conicus produced 14.1 percent of the number of viable cypselae as in uninfested heads. Not all taxa are impacted as much as C. canescens, particularly those with later flowering phenology (Louda 1998) . R. W. Pemberton (2000) reported that 22 Cirsium taxa in North America are known hosts of R. conicus. I suspect that the number is higher. During my field work I have observed that the heads of many Cirsium species are heavily parasitized, although I have not determined which of these are infested by R. conicus and which by native seedhead parasites. The long-term impacts of R. conicus and other biocontrol agents on native thistles, particularly rare taxa, remain to be determined.
Species Cirsium arvense
Canada thistle is an herbaceous perennial
stems 1½-4 feet
tall, prickly leaves and an extensive creeping
. Stems are
branched, often slightly hairy
, and ridged
. Leaves are lance-shaped,
and are borne singly
and alternately along the stem. Rose-purple, lavender, or sometimes
white flower heads
appear from June through October, generally, and
occur in rounded
, umbrella-shaped clusters
The small, dry, single-seeded fruits of Canada thistle, called achenes, are 1-1½ inches long and have a feathery structure attached to the seed base . Many native species of thistle occur in the U.S., some of which are rare. Because of the possibility of confusion with native species, Canada thistle should be accurately identified before any control is attempted.
Perennials, dioecious or nearly so, 30-120(-200) cm; colonial from deep-seated creeping roots producing adventitious buds. Stems 1-many, erect, glabrous to appressed gray-tomentose; branches 0-many, ascending . Leaves: blades oblong to elliptic , 3-30 × 1-6 cm, margins plane to revolute , entire and spinulose , dentate , or shallowly to deeply pinnatifid , lobes well separated, lance-oblong to triangular-ovate, spinulose to few-toothed or few-lobed near base, main spines 1-7 mm, abaxial faces glabrous to densely gray-tomentose, adaxial green, glabrous to thinly tomentose ; basal absent at flowering, petioles narrowly winged , bases tapered; principal larger cauline proximally winged-petiolate, distally sessile, well distributed, gradually reduced, not decurrent; distal cauline becoming bractlike, entire, toothed, or lobed, spinulose or not. Heads 1-many, borne singly or in corymbiform or paniculiform arrays at tips of main stem and branches. Peduncles 0.2-7 cm. Involucres ovoid in flower, ± campanulate in fruit, 1-2 × 1-2 cm, arachnoid tomentose, ± glabrate . Phyllaries in 6-8 series, strongly imbricate, (usually purple-tinged), ovate (outer) to linear (inner), abaxial faces with narrow glutinous ridge , outer and middle appressed, entire, apices ascending to spreading , spines 0-1 mm (fine) ; apices of inner phyllaries flat, ± flexuous , margins entire to minutely erose or ciliolate . Corollas purple (white or pink) ; staminate 12-18 mm, (remaining longer than pappus when head is fully mature ), tubes 8-11 mm, throats 1-1.5 mm, lobes 3-5 mm; pistillate 14-20 mm, (overtopped by pappi in fruit), tubes 10-15 mm, throats ca. 1 mm, lobes 2-3 mm; style tips 1-2 mm. Cypselae brown, 2-4 mm, apical collar not differentiated; pappi 13-32 mm, exceeding corollas. 2n = 34. Flowering summer (Jun-Oct). [source]
Numerous variants of Cirsium arvense have been named based upon such features as pubescence , extent of leaf division, and spininess. Although extreme variants can be strikingly different, they are connected by such a web of intermediates that there seems to be little value in according any of them formal taxonomic recognition. [source]
Flowers: Bloom Period: April, May, June, July, August. • Flower Color: cream, lavender, magenta, purple, tan, violet
Size: 24-36" tall.
, pastures, roadsides, forest
Nuzzo (1997) cites that C. arvense occurs in nearly every upland herbaceous community within its range , and is a particular threat in prairie communities and riparian habitats . Throughout its range it is common on roadsides, in oldfields, croplands, and pastures, in deep, well-aerated, mesic soils. In eastern North America, it occasionally occurs in relatively dry habitats, including sand dunes and sandy fields, as well as on the edges of wet habitat, including stream banks, lakeshores, cleared swamps , muskegs and ditches. It is shade intolerant . It grows on all but waterlogged, poorly aerated soils, including clay , clay loam, silt loam , sandy loam, sandy clay, sand dunes, gravel , limestone, and chalk , but not peat. Zouhar (2001) reports that it can tolerate soils with up to 2% salt content . It grows best between 0 - 32 °Celsius. It tolerates annual precipitation ranging from 305-1015 mm per year and grows best with 400-750 mm of precipitation per year.
Canada thistle grows in barrens , glades , meadows, prairies, fields, pastures, and waste places. It does best in disturbed upland areas but also invades wet areas with fluctuating water levels such as streambank sedge meadows and wet prairies.
Typically found at an altitude of 0 to 2,848 meters (0 to 9,344 feet).
- Nuzzo (1997) states that C. arvense threatens natural communities by directly competing with and displacing native vegetation, decreasing species diversity , and changing the structure and composition of some habitats . Species diversity in an "undisturbed" Colorado grassland was inversely proportional to the relative frequency of C. arvense. It presents an economic threat to farmers and ranchers. Infestations reduce crop yield through competition for water, nutrients and minerals, and through interference with harvest . In Canada, the major impact of C. arvense is in agricultural land, and in natural areas that have been disturbed or are undergoing restoration . In the United States, it is a host for bean aphid and stalk borer , insects that affect corn and tomatoes, and for sod-web worm, which damages corn. In Bulgaria, C. arvense is a host for the cucumber mosaic virus. In addition to reducing forage and pasture production , it may scratch grazing animals, resulting in small infections . Zouhar (2001) reports that it has been identified as a management problem in many national parks and on TNC (The Nature Conservancy) preserves in the upper Midwest, the Great Plains states, and the Pacific Northwest. Infestations of C. arvense may contribute to the elimination of endangered and/or endemic plant species, such as the Colorado butterfly plant in Wyoming.
- Natural communities that are threatened by Canada thistle include non-forested plant communities such as prairies, barrens , savannas , glades , sand dunes, fields and meadows that have been impacted by disturbance . As it establishes itself in an area, Canada thistle crowds out and replaces native plants, changes the structure and species composition of natural plant communities and reduces plant and animal diversity . This highly invasive thistle prevents the coexistence of other plant species through shading, competition for soil resources and possibly through the release of chemical toxins poisonous to other plants .
- Canada thistle is declared a "noxious weed " throughout the U.S. and has long been recognized as a major agricultural pest, costing tens of millions of dollars in direct crop losses annually and additional millions costs for control. Only recently have the harmful impacts of Canada thistle to native species and natural ecosystems received notable attention.
- Management of Canada thistle can be achieved through hand-cutting, mowing, controlled burning , and chemical means, depending on the level of infestation and the type of area being managed. Due to its perennial nature, entire plants must be killed in order to prevent regrowth from rootstock . Hand-cutting of individual plants or mowing of larger infestations should be conducted prior to seed set and must be repeated until the starch reserves in the roots are exhausted. Because early season burning of Canada thistle can stimulate its growth and flowering, controlled burns should be carried out late in the growing season for best effect.
- In natural areas where Canada thistle is interspersed with desirable native plants, targeted application of a systemic herbicide such as glyphosate (e.g. , Roundup® or Rodeo®), which carries plant toxins to the roots, may be effective. For extensive infestations in disturbed areas with little desirable vegetation, broad application of this type herbicide may be the most effective method. Repeated applications are usually necessary due to the long life of seeds stored in the soil.
Canada thistle produces
of bristly-plumed seeds which
are easily dispersed by the wind. Most of the seeds germinate
a year, but some may remain viable in the soil for up to twenty years
or more. Vegetative reproduction in Canada thistle is aided by a
capable of sending out lateral
as deep as 3
feet below ground
, and from which shoots
sprout up at frequent intervals.
It also readily regenerates from root fragments less than an inch
Nuzzo (1997) states that the weed spreads primarily by vegetative means (by its root), and secondarily by seed. The root system can be extensive, growing horizontally as much as 6 m in one season , and individual roots live up to two years. Most patches spread at the rate of 1-2 m/year. Under good growing conditions, female plants produce an average of 29 flowering shoots/square meter, each with an average of 41 heads/shoot and 59 seeds/head. A single plant produces an average of 1500 and up to 5300 seeds. Multiple plants produced 100-64,300 viable seeds/m2 in Australia and up to 30,200/m2 in Holland.
Germination may be affected by ecotype, temperature , day length , depth of seed burial, substrate stratification , and seed freshness. Seeds from "male" plants are smaller and percent germination is lower. Seeds germinate best in warm temperatures 20 - 40 degrees Celsius, with alternating light and dark periods. At lower temperatures germination is aided by high light intensity . Germination at higher temperatures can help ensure that maximum germination takes place during warmer periods of the year. Seeds are somewhat tolerant of heat, and some were still viable after 10 minutes at 102 degrees Celsius and 2 minutes at 262 degrees Celsius, although viability was decreased at these temperatures compared to unheated controls . The seeds germinate over a wide range of soil moisture.
Duration: Biennial, Perennial
Culture: Space 15-18" apart.
Soil: Minimum pH: 5.1 • Maximum pH: 9.0
Sunlight: Sun Exposure: Full Sun .
Moisture: Drought Tolerance: High
Temperature: Cold Hardiness: 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a. (map)
- Whittaker & Margulis,1978
- Haeckel, 1866
- Cavalier-Smith, 1981
- Sinnott, 1935 ex Cavalier-Smith, 1998
t communities of Beaverhead, Silver Bow, and
- Brongniart, 1843
- Takhtajan, 1967
- Takhtajan Ex Reveal, 1992
- Order: 8-19. () - Lindley, 1833
- Superorder: Campanulanae () - Takhtajan Ex Reveal, 1992
- Subclass: Asteridae () - Takhtajan, 1967
- Class: t communities of Beaverhead, Silver Bow, and () - Brongniart, 1843
- Subphylum: Euphyllophytina ()
- Phylum: Tracheophyta () - Sinnott, 1935 ex Cavalier-Smith, 1998
- Subkingdom: Viridaeplantae () - Cavalier-Smith, 1981
- Kingdom: Plantae () - Haeckel, 1866 - Plants
Breea arvensis (L.) Less. • Carduus arvensis (L.) Robson • Cephalonoplos arvense (L.) Fourr. • Cirsium arvense var. argenteum (Vest) Fiori • Cirsium arvense var. horridum Wimmer and Grab. • Cirsium arvense var. integrifolium Wimmer and Grab. • Cirsium arvense var. mite Wimmer and Grab. • Cirsium arvense var. vestitum Wimmer and Grab. • Cirsium incanum (Gmel.) Fisch. • Cirsium setosum (Willd.) Bess. Ex Bieb. • Cnicus arvensis (L.) Hoffm. • Serratula arvensis L.
Status: Accepted Name
Last scrutiny: 17-Nov-09
Members of the genus Cirsium
ZipcodeZoo has pages for 146 species, subspecies, varieties, forms, and cultivars in this genus. Here are just 100 of them:
C. altissimum (Roadside Thistle) · C. amblylepis (Mt. Tamalpais Thistle) · C. andersonii (Anderson's Thistle) · C. andrewsii (Franciscan Thistle) · C. araneans (Jeweled Thistle) · C. arcuum (Powderpuff Thistle) · C. aridum (Cedar Rim Thistle) · C. arizonicum (Arizona Thistle) · C. arizonicum var. arizonicum (Arizona Thistle) · C. arizonicum var. nidulum (Arizona Thistle) · C. arvense (Californian Thistle) · C. barnebyi (Barneby's Thistle) · C. brevifolium (Palouse Thistle) · C. brevistylum (Clustered Thistle) · C. calcareum (Cainville Thistle) · C. californicum var. californicum (California Thistle) · C. callilepis var. callilepis (Fringebract Thistle) · C. canalense (Canal Thistle) · C. canescens (Platte Thistle) · C. canovirens (Gray Green Thistle) · C. canum (Queen Anne's Thistle) · C. carolinianum (Carolina Thistle) · C. chellyense (Queen Thistle) · C. chuskaense (Monarch Thistle) · C. ciliolatum (Ashland Thistle) · C. clavatum (Fish Lake Thistle) · C. clokeyi (Charleston Mountain Thistle) · C. congdonii (Rosette Thistle) · C. crassicaule (Slough Thistle) · C. crassum (Thistle) · C. cymosum (Peregrine Thistle) · C. diacanthus (Ivory Thistle) · C. discolor (Field Thistle) · C. douglasii (Douglas Thistle) · C. douglasii var. breweri (Douglas' Thistle) · C. douglasii var. breweri (Petr.) Keil & C.Turner (Douglas' Thistle) · C. douglasii var. douglasii (Douglas' Thistle) · C. douglasii var. douglasii DC. (Douglas' Thistle) · C. drummondii (Drummond Thistle) · C. eatonii (Eaton Thistle) · C. eatonii var. eatonii (Eaton's Thistle) · C. edule (Edible Thistle) · C. engelmannii (Engelmann Thistle) · C. eriophorum (Woolly Thistle) · C. erosum (Glory Thistle) · C. flodmanii (Flodman Thistle) · C. foliosum (Drummond's Thistle) · C. fontinale (Fountain Thistle) · C. fontinale (Greene) Jeps. var. campylon (H.K.Sharsmith) Pilz ex Keil & C.Turner (Fountain Thistle) · C. fontinale var. campylon (Mt Hamilton Thistle) · C. fontinale var. fontinale (Fountain Thistle) · C. fontinale var. obispoense (Chorro Creek Bog Thistle) · C. gilense (Gila Thistle) · C. grahamii (Graham's Thistle) · C. griseum (Gray Thistle) · C. hallii (Hall's Thistle) · C. helenioides (Melancholy Thistle) · C. heterophyllum (Curly Head) · C. hillii (Hill's Thistle) · C. hookerianum (Hooker Thistle) · C. horridulum (Bristly Thistle) · C. horridulum Michx. var. vittatum (Small) R.W.Long (Yellow Thistle) · C. horridulum var. horridulum (Yellow Thistle) · C. horridulum var. vittatum (Yellow Thistle) · C. humboldtense (Humboldt County Thistle) · C. hydrophilum (Suisun Thistle) · C. hydrophilum var. hydrophilum (Suisun Thistle) · C. hydrophilum var. vaseyi (Vasey's Thistle) · C. inornatum (Cloudcroft Thistle) · C. iowense (Iowa Thistle) · C. japonicum (Japanese Thistle) · C. japonicum 'Pink Beauty' (Japanese Thistle) · C. kamtschaticum (Kamchatka Thistle) · C. laterifolium (Porcupine Thistle) · C. lecontei (Le Conte's Thistle) · C. loncholepis (La Graciosa Thistle) · C. longistylum (Long-Styled Thistle) · C. mendocinum (Mendocino Thistle) · C. mexicanum (Mexican Thistle) · C. modestum (Lacy Thistle) · C. mohavense (Mohave Thistle) · C. murdockii (Murdock's Thistle) · C. muticum (Swamp Thistle) · C. navajoense (Navajo Thistle) · C. neomexicanum (Lavender Thistle) · C. neomexicanum var. neomexicanum (New Mexico Thistle) · C. neomexicanum var. utahense (Utah Thistle) · C. nuttallii (Nutalls Thistle) · C. occidentale (Cobweb Thistle) · C. occidentale (Nutt.) Jeps. var. californicum (Gray) Keil and C.Turner (California Thistle) · C. occidentale var. californicum (Cobwebby Thistle) · C. occidentale var. compactum (Compact Cobwebby Thistle) · C. occidentale var. occidentale (Cobwebby Thistle) · C. occidentale var. venustum (Cobwebby Thistle) · C. ochrocentrum (Yellow-Spine Thistle) · C. olivescens (Summer Thistle) · C. oreophilum (Crow Thistle) · C. osterhoutii (Osterhout's Thistle) · C. ownbeyi (Ownbey's Thistle) · C. pallidum (Pale Thistle)
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- A biological survey of the sand dune region on the south shore of Saginaw Bay, Michigan. Prepared under the direction of Alexander G. Ruthven. Lansing, Mich.: Wynkoop, Hallenbeck, Crawford co., state printers, 1911. url p. 119, p. 182, p. 183, p. 195, p. 209, p. 216, p. 325, p. 47.
- A botanical exploration of the north shore of the gulf of St. Lawrence including an annotated list of the species of vascular plants, Ottawa, F. A. Acland, printer, 1922. url p. 112, p. 125, p. 26, p. 28.
- A contribution to our knowledge of seedlings; by the Right Hon. Sir John Lubbock. London: K. Paul, Trench, Trübner, & co., ltd., 1892. url .
- A dictionary of American plant names, compiled by Willard N. Clute. Joliet, Ill., W. N. Clute, 1923. url p. 80.
- A handbook of systematic botany / by Dr. E. Warming with a revision of the fungi by Dr. E. Knoblauch, tr. and ed. by M. C. Potter. New York: Macmillan & Co., 1895. url p. 568.
- A handbook of systematic botany; with a revision of the fungi, by E. Knoblauch; tr. and ed. by M.C. Potter. London, Swan url p. 568.
- A manual flora of Egypt / by Reno Muschler. With a preface by Paul Ascherson and Georg Schweinfurth. Berlin, R. Friedlaender, 1912. url p. 1044.
- A manual of poisonous plants, chiefly of eastern North America, with brief notes on economic and medicinal plants, and numerous illustrations, Cedar Rapids, Ia., The Torch Press, 1911. url , .
- A manual of poisonous plants: chiefly of eastern North America, with brief notes on economic and medicinal plants, and numerous illustrations / by L.H. Pammel. Cedar Rapids, Iowa: Torch Press, 1910-1911. url p. 798, p. 799.
- A manual of the flora of northern Idaho /Carl Epling and Joe Ewan. 4 1941 1941. url p. 857.
- A naturalist in the Great Lakes region, by Elliot Rowland Downing. .. Chicago, Ill., The University of Chicago Press[c1922] url , , p. 317, p. 327.
- A preliminary classification of the plant communities of northeastern Montana / Robert L. DeVelice [et al.]. Helena, MT: Montana Natural Heritage Program, c1991. url , , , , , , , , , , , .
- A provisional list of the parasitic fungi of Wisconsin. Madison, 1914 url p. 911.
- A study of the vegetation of southeastern Washington and adjacent Idaho. .. Lincoln, Neb. url p. 110.
- A talk on weeds; an address delivered before the county road school, Clinton County, Iowa, 1910, with an appendix describing a few weeds, by L. H. Pammel. .. Ames? Ia., c1910 url p. 16.
- A text-book of grasses with especial reference to the economic species of the United States, by A. S. Hitchcock. New York, Macmillan, 1914. url p. 75.
- A text-book of grasses: with especial reference to the economic species of the United States / by A.S. Hitchock. New York: Macmillan, 1914. url p. 75.
- A university text-book of botany. New York, Macmillan, 1910. url p. 556.
- A vegetation index of biotic integrity for small-order streams in southwest Montana and a floristic quality assessment for western Montana wetlands / [Helena, Mont.: Montana Natural Heritage Program, c2005]. url .
- Aeration and air-content; the role of oxygen in root activity, by Frederic E. Clements. Washington, Carnegie Institution of Washington, 1921. url p. 144.
- American honey plants; together with those which are of special value to the beekeeper as sources of pollen. Hamilton, Ill., American Bee Journal, 1920. url p. 150, p. 290, p. 48.
- Ames forester. .. Ames, Ia., The Forestry club of the Iowa state college, 1913- url p. 285.
- An illustrated flora of the northern United States, Canada and the British possessions: from Newfoundland to the parallel of the southern boundary of Virginia and from the Atlantic Ocean westward to the 102nd meridian / by Nathaniel Lord Britton and Hon. Addison Brown. New York: Scribner, 1913. url p. 553.
- An integrative biological assessment of sites in the Custer National Forest, Ashland Ranger District: a report to the Custer National Forest, Ashland Ranger District / [Helena, Mont.]: Montana Natural Heritage Program:  url .
- An introduction to historical plant geography, by E. V. Wulff. .. authorized translation by Elizabeth Brissenden. Foreword by Elmer D. Merrill. Waltham, Mass., Chronica Botanica Co., 1943. url p. 113, p. 216.
- Annals of applied biology. [Wellesbourne, Warwick, etc.]Association of Applied Biologists [etc.] url p. 146, p. 154.
- Annotated list of the ferns and flowering plants of New York state, by Homer D. House. Albany, The University of the state of New York, 1924. url p. 745.
- Annual report / Albany: University of the State of New York, 1902-1918. url p. 158, p. 170, p. 248.
- Annual report of the Bureau of American Ethnology to the Secretary of the Smithsonian Institution. Washington: U. S. Govt. Print. Off., 1897- url p. 304.
- Annual report of the Commissioner of Agriculture. .. Albany: State of New York, Dept. of Agriculture, 1894-1911. url p. 745.
- Annual report of the Michigan Academy of Science. Lansing, Mich.: The Academy, 1916-1921. url p. 271.
- Annual report of the Quebec Society for the Protection of Plants from Insects and Fungous Diseases. Quebec: The Society, 1909-1920. url .
- Appendices A-E: terrestrial resources injury assessment report: upper Clark Fork River NPL sites. Helena?, Mont.: Dept. of Justice?, 1995 url .
- Appendix C., vegetation/agricultural resources of the Beal Project area / prepared for Beal Mountain Mining, Inc.; prepared by Ken L. Scow, L. Dean Culwell. Helena, Mont.: Western Technology and Engineering,  url .
- Assessment of the Red Rock River subbasin and wetlands of the Centennial Valley / Helena, Mont.: Montana Natural Heritage Program, c2009. url p. 22, p. 32.
- Bartonia;proceedings of the Philadelphia botanical club. .. 61 2002 Philadelphia, Philadelphia Botanical Club, Academy of Natural Sciences. url p. 173, p. 27, p. 36, p. 51.
- Bee culture in Maine, Waterville, Sentinel publishing company, 1918 url .
- Beekeeping in the Kootenays, British Columbia. Nelson, B. C., Beekeepers' Association of British Columbia, Kootenay Division, 1918. url .
- Beekeeping in the interior of British Columbia. .. [n.p.]British Columbia honey producers' association.1922. url .
- Biodiversity and representativeness of research natural areas on national wildlife refuges in Montana, designated areas within Benton Lake, Charles M. Russell, Lake Mason, Medicine Lake, and Red Rock final report / submitted to the U.S. Fish and Wildlife Service; prepared by Stephen V. Cooper and Bonnie L. Heidel. Helena, MT: Montana Natural Heritage Program, c1999 url , p. 21, p. 26, p. 30, p. 38, p. 45, p. 46, p. 49.
- Biological survey of a prairie landscape in Montana's glaciated plains: final report / Helena, Mont.: Montana Natural Heritage Program: 2001. url , , , , , , .
- Biological survey of the Mount Desert Region, conducted by William Procter... From the Mount Desert Island Biological Laboratory, Mount Desert Island, Maine. Philadelphia, The Wistar Institute of Anatomy and Biology, 1927-1946. url p. 218.
- Botanical abstracts. Baltimore, Williams & Wilkins Co. url p. 243.
- Botanical and vegetation survey of Carter County, Montana, Bureau of Land Management-administered lands / prepared by Jim Vanderhorst, Stephen V. Cooper, and Bonnie L. Heidel; prepared for United States Department of the Interior, Bureau of Land Management. Helena, MT: Montana Natural Heritage Program,  url , p. 31.
- Brigham Young University science bulletin. 4 1964 Provo, Utah: Brigham Young University, [1955-1976] url p. 14.
- British journal of entomology and natural history. [London]: British Entomological and Natural History Society, 1988- url , , , , p. 101, p. 111, p. 115, p. 151, p. 171, p. 175, p. 181, p. 209, p. 71, p. 72, p. 73, p. 75, p. 81.
- Britton, N. L. (ed.). North American flora. 6 1922 [New York]New York Botanical Garden. url p. 34, p. 511, p. 76, p. 77, p. 82, p. 845, p. 871, p. 949.
- Budd's flora of the Canadian Prairie Provinces / [Ottawa]: Research Branch, Agriculture Canada, 1987. url p. 742, p. 743, p. 744.
- Bulletin / Arizona Agricultural Experiment Station. Tucson: Agricultural Experiment Station, University of Arizona, 1890-1960. url p. 644.
- Bulletin / Illinois Natural History Survey. Urbana, State of Illinois, Dept. of Registration and Education, Natural History Survey Division, 1918-1985. url p. 391, p. 392.
- Bulletin / Ohio Biological Survey. Columbus, Ohio: Ohio State University, 1913- url p. 235.
- Bulletin / U.S. Department of Agriculture, Bureau of Plant Industry. Washington: G.P.O., 1901-1913. url p. 18.
- Bulletin / University of Montana. Missoula: University of Montana, 1901-1910. url p. 47.
- Bulletin of the British Museum (Natural History). London: BM(NH) url p. 269.
- Bulletin of the U.S. Department of Agriculture. [Washington, D.C.?]: Supt. of Docs., Govt. Print. Off., 1913-1923. url p. 2, p. 2.
- Bulletin of the Wisconsin Natural History Society. Milwaukee, The Society, [1900-1920] url p. 153, p. 36, p. 37, p. 39, p. 76.
- Carnegie Institution of Washington publication. Washington, Carnegie Institution of Washington, 1902- url p. 144, p. 378, p. 59.
- Catalog of Ohio vascular plants, arranged according to the phyletic classification; with notes on the geographical distribution in the state, based mainly on specimens in the State Herbarium, Botanical Laboratory, the Ohio State Univ Columbus, The Ohio State University, 1914. url .
- Catalog of Ohio vascular plants: arranged according to the phyletic classification: with notes on the geographical distribution in the state, based mainly on specimens in the State Herbarium, Botanical Laboratory, the Ohio State Uni by John H. Schaffner. Columbus: Ohio State University, 1914. url p. 235.
- Catalog of hymenoptera in America north of Mexico / prepared cooperatively by specialists on the various groups of Hymenoptera under the direction of Karl V. Krombein. .. [et al.]. Washington: Smithsonian Institution Press, 1979- url , , , .
- Catalogue of scientific papers (1800-1900) Comp. by the Royal society of London. Cambridge, C. J. Clay and sons, 1867-1902; url p. 39, p. 818, p. 863.
- Catalogue of scientific papers, 1800-1900. Compiled by the Royal Society of London. London, C.J. Clay and Sons, 1867-1902 [etc.] Cambridge, Cambridge University Press, 1914-25. url p. 39, p. 497, p. 818, p. 863.
- Catalogue of the Lepidoptera Phalænæ in the British museum. London: Printed by Order of the Trustees, 1898-19. url p. 161.
- Catalogue of the books, manuscripts, maps and drawings in the British Museum (Natural History) London: BM(NH), 1903-1940. url p. 1193, p. 1193, p. 1737.
- Catalogue of the flowering plants and ferns of Connecticut growing without cultivation / by Charles Burr Graves. .. [et al.]; Committee of the Connecticut Botanical Society. Hartford: Printed for the State Geological and Natural History Survey, 1910. url p. 406.
- Checklist of plants of the Ottawa District. Ottawa, 1958. url p. 87.
- Circle west vegetation baseline study: final report / by Richard Prodgers. Helena: Energy Division, Montana Dept. of Natural Resources and Conservation,  url p. 106, p. 98.
- Classification of the plant communities of Beaverhead, Silver Bow, and Madison Counties, Montana / for Bureau of Land Management, State Office, Billings, Montana. Helena, Mt.: Montana Natural Heritage Program,  url p. 148, p. 23, p. 28, p. 30, p. 71, p. 76, p. 81, p. 87.
- Clovers and how to grow them / New York: Orange Judd Company, 1906. url .
- Clovers and how to grow them, New York, Orange Judd company, 1912. url , .
- Clovers and how to grow them, by Thomas Shaw. New York: Orange Judd company, 1906. url p. 235.
- Common weeds of the Canadian Prairies; Ottawa, Queen's Printer, 1963. url p. 11, p. 15, p. 31, p. 67.
- Compositae newsletter. Columbus, Ohio: Dept. of Botany, Ohio State University, 1975- url p. 16, p. 26, p. 27, p. 28, p. 37, p. 5, p. 5.
- Compte rendu du Congre?s international d'essais de semences. Discussions at the International Seed Testing Conference. Verhandlungen der Internationalen Konferenz fu?r Samenpru?fung a?/in Copenhague (Danemark), 6.- 10. VI. 1921. Hamburg, Druck von Lu?tcke & Wulff url , , , , .
- Conservation status of Spiranthes diluvialis Sheviak in Montana. Helena: Montana Natural Heritage Program, 1998 url p. 27.
- Contributions from the Botanical Laboratory and the Morris Arboretum of the University of Pennsylvania. Philadelphia: [s.n., url .
- Contributions from the Hull Botanical Laboratory. [Chicago: University of Chicago Press, 1895- url p. 49.
- Contributions from the Osborn Botanical Laboratory. [New Haven?]Osborn Botanical Laboratory, Yale University, url p. 335, p. 364, p. 368.
- Contributions from the University of Michigan Herbarium. 13 1978 Ann Arbor: University Herbarium, University of Michigan, 1939- url p. 68.
- Contributions to Canadian botany / by Jas. M. Macoun. Ottawa: [s. n.], 1894-1906. url p. 170.
- Contributions towards a Cybele hibernica, being outlines of the geographical distribution of plants in Ireland. Dublin.E. Ponsonby, 1898. url .
- Control series bulletin / Massachusetts Agricultural Experiment Station. Amherst, University of Massachusetts. url p. 4.
- Cooperative economic insect report. Hyattsville, MD. [etc.]Plant Protection and Quarantine Programs Animal and Plant Health Service. url p. 14, p. 146, p. 418, p. 452, p. 580, p. 703, p. 780, p. 837.
- Cryptogamic plants of the USSR. (Flora sporovykh rastenii SSSR) Translated from Russian. Jerusalem[Published for the National Science Foundation, Washington, D.C. by the Israel Program for Scientific Translations, 19 - url p. 107, p. 108, p. 172, p. 503, p. 93.
- Danish fungi as represented in the herbarium of E. Rostrup / revised by J. Lind. Copenhagen: Gyldendalske boghandel, 1913. url p. 162, p. 225, p. 302, p. 325, p. 366, p. 424, p. 467, p. 511, p. 519, p. 533, p. 536, p. 57, p. 60.
- Deadman Gulch timber sale environmental assessment / Montana Department of Natural Resources and Conservation, Missoula Unit. Missoula, Mont.: The Dept., 2003 url p. 8.
- Desirables and weeds for roadside management: a northern Rocky Mountain catalogue / [Helena]: Available through the National Technical Information Service, 1997] url , .
- Dictionary of biological equivalents, German-English, by Ernst Artschwager. .. Baltimore, The Williams & Wilkins company, 1930. url p. 26, p. 75.
- Diptera Danica: genera and species of flies hitherto found in Denmark. Copenhagen, G.E.C. Gad, 1907-1927. url p. 269.
- Dirty Ike salvage environmental assessment / Montana Department of Natural Resources and Conservation, Southwestern Land Office, Missoula Unit. Missoula, Mont.: The Dept.,  url p. 15.
- Diseases of plants induced by cryptogamic parasites: introduction to the study of pathogenic Fungi, slime-Fungi, bacteria, & Algae / London; Longmans, Green & co., 1897. url .
- Draft environmental assessment: Lewis and Clark Caverns State Park aerial weed spraying project. [Bozeman, MT]: Montana Fish, Wildlife & Parks,  url .
- Ecological inventory of wetland sites in the Thompson-Fisher conservation easement / Helena, MT: Montana Natural Heritage Program, c2002. url , , , .
- Ecologically significant wetlands in the Missouri headwaters: Jefferson, lower Madison, lower Gallatin, and upper Red Rock River watersheds / Helena, Mont.: Montana Natural Heritage Program, c2004. url , , , , .
- Effects of highways on wildlife and fish with special reference to Montana a ProCite literature collection / Bozeman, Mont.: Fish and Wildlife Management Program, Montana State University, 2001 url .
- Effects of mineral levels on physiology and morphology of plants / by Johannes Bernardus Balthasar Brolmann. 1968. url p. 9.
- Entomological news. [Philadelphia]American Entomological Society, 1925- url p. 112, p. 115, p. 122, p. 123, p. 151, p. 16, p. 161, p. 162, p. 483, p. 485, p. 486, p. 491, p. 79.
- Erigenia: journal of the Illinois Native Plant Society. Carbondale, Ill.: The Society, 1982- url p. 16, p. 21, p. 25, p. 55, p. 56, p. 6, p. 68, p. 7, p. 72, p. 75, p. 8, p. 86, p. 88, p. 89, p. 91, p. 92, p. 94, p. 95.
- Evans, J.E. 1984. Canada thistle (Cirsium arvense): a literature review of management practices. Natural Areas Journal 4(2):11-21.
- Experiments in elementary agriculture; Cedar Falls, Iowa, S. E. Green & co., c1915. url p. 9.
- Expert rebuttal opinions regarding injuries to terrestrial resources, Clark Fork River Basin, MT / Boulder, CO: Hagler Bailey Consulting, 1995. url .
- Farm weeds of Canada / by George H. Clark and James Fletcher; with illustrations by Norman Criddle. Ottawa: Dept. of Agriculture, 1923 url p. 164, p. 185.
- Farm weeds of Canada, by George H. Clark and James Fletcher. With illustrations by Norman Criddle. Published by direction of the Hon. Sydney A. Fisher, Minister of Agriculture, Ottawa, 1909. Ottawa: Govt. Print. Bureau,  url p. 164.
- Field book of American wild flowers; being a short description of their character and habits, a concise definition of their colors, and incidental references to the insects which assist in their fertilization, by F. Schuyler Mathews. 1912 New York, Putnam,  url fig. 263, p. 523, p. 574.
- Field book of american wild flowers; being a short description of their character and habits, a concise definition of their colors, and incidental references to the insects which assist in their fertilization, by F. Schuyler Mathews... with numerous reproductions of water colors and pen-and-ink studies from nature by the author. New York, G.P. Putnam, 1902. url p. 540.
- Fieldbook of Illinois wild flowers; six hundred fifty of the more common flowering plants in the state. Urbana, 1936. url p. 384.
- Fifty years of botany; golden jubilee volume of the Botanical Society of America, edited by William Campbell Steere. New York, McGraw-Hill, 1958. url p. 406, p. 416.
- Fish Creek salvage environmental assessment / Montana Department of Natural Resources and Conservation, Southwestern Land Office, Missoula Unit. Missoula, Mont.: The Dept., October 2003. url p. 40.
- Flora of Berkshire County, Massachusetts. Boston, Printed for the Society, 1922. url , , , p. 363.
- Flora of Glacier National Park, Montana, by Paul C. Standley. Washington, Govt. Print. Off., 1921. url p. 438.
- Flora of Illinois, containing keys for identification of flowering plants and ferns. Notre Dame, Ind., University of Notre Dame Press, 1963. url p. 268.
- Flora of Indiana, by Charles C. Deam. Indianapolis, Wm. B. Burford printing co., contractor for state printing and binding, 1940. url p. 1001, p. 1002.
- Flora of Japan: in English: combined, much revised and extended translation / by the author of his Flora of Japan (1953) and Flora of Japan, Pteridophyta (1957); edited by Frederick G. Meyer and Egbert H. Walker. Washington: Smithsonian Institution, 1965. url p. 912.
- Flora of Lancaster County: being descriptions of the seed-plants growing naturally in Lancaster County, Pennsylvania / by John Kunkel Small and Joel Jackson Carter. New York: The authors, 1913. url p. 311.
- Flora of Lancaster County; being descriptions of the seed- plants growing naturally in Lancaster County, Pennsylvanial. By John Kunkel Small and Joel Jackson Carter. New York, 1913. url p. 311.
- Flora of New Bedford and the shores of Buzzards Bay, with a procession of the flowers. New Bedford [Mass.]E. Anthony, 1911. url p. 55.
- Flora of Vermont. List of ferns and seed plants growing without cultivation. Prepared by Vermont Botanical Club. Burlington, Vt., Free Press Print. Co., 1915. url p. 253.
- Flora of southeastern Washington and adjacent Idaho / by Charles V. Piper and R. Kent Beattie. Lancaster, Pa.: New Era, 1914. url p. 259, p. 260.
- Flora of the District of Columbia and vicinity. By A.S. Hitchcock and Paul C. Standley, with the assistance of the botanists of Washington. WashingtonGovt. print. off.1919 url p. 292.
- Flora of the Indiana dunes, a handbook of the flowering plants and ferns of the lake Michigan Coast of Indiana and of the Calumet District, by Donald Culross Peattie. Chicago, Field Museum of Natural History, 1930. url p. 397.
- Flora of the Queen Charlotte Islands. [Ottawa: Queen's Printer], 1968-. url p. 114, p. 530, p. 615.
- Flora of the U.S.S.R. [Springfield, Va.: Israel Program for Scientific Translations; 1968- url p. 208, p. 53, p. 90.
- Flora of the northwest coast, including the area west of the summit of the Cascade Mountains, from the forty-ninth parallel south to the Calapooia Mountains on the south border of Lane County, Oregon. Lancaster, Pa., Press of the New Era Printing Company, 1915. url , .
- Flora of the northwest coast: including the area west of the summit of the Cascade Mountains, from the forty-ninth parallel south to the Calapooia Mountains on the south border of Lane County, Oregon / by Charles V. Piper and R. Kent Beattie. Lancaster, Pa.: Press of the New era printing company, 1915. url p. 394, p. 395.
- Flora of the southeastern Washington and adjacent Idaho, Lancaster, Pa., Press of the New Era Printing Company, 1914. url .
- Flora of the state of Washington / by Charles V. Piper. Washington: G.P.O., 1906 url p. 609.
- Flora of the state of Washington. By Charles V. Piper. Washington, Govt. Print. Off., 1906. url p. 609.
- Florula Mortolensis. An enumeration of the plants growing wild at La Mortola. Ventimiglia, Billi, 1905. url .
- Flowering plants of the Riviera: a sescriptive account of 1800 of the more interesting species / by H. Stuart Thompson; with an introduction on Riviera vegetation by A. G. Tansley London; New York: Longmans, Green, 1914. url p. 139.
- Foundations of botany / by Joseph Y. Bergen. Boston: Ginn, 1901. url p. 389, p. 389.
- Foundations of botany, Boston, Ginn & Co., 1901. url .
- Foundations of botany, by Joseph Y. Bergen. Boston, Ginn & co., 1904. url p. 389.
- Fundamentals of botany / by C. Stuart Gager. Philadelphia: P. Blakiston's Son & Co., c1916. url p. 486, p. 626.
- Fundamentals of botany, Philadelphia, P. Blakiston's son & co., 1916. url , .
- Fundamentals of botany, by C. Stuart Gager. With 435 illustrations. Philadelphia, P. Blakiston, 1916. url p. 486, p. 626.
- Fundamentals of botany. Philadelphia, Blakiston url p. 486, p. 626.
- Fungous diseases of plants, Boston, Ginn and company[c1909] url p. 392, p. 486, p. 500.
- Fungous diseases of plants, with chapters on physiology, culture methods and technique, by Benjamin Minge Duggar. Boston, Ginn and company, [c1909] url p. 392, p. 486, p. 500.
- Fungous diseases of plants: with chapters on physiology, culture methods and technique / Boston; Ginn, [c1909] url , , , .
- Fungous diseases of plants; with chapters on physiology, culture methods and techniques. Boston, Ginn url p. 392, p. 422, p. 486, p. 500.
- Grasses and how to grow them in North America / by Thomas Shaw. St. Paul: Webb publishing co., 1910. url p. 100, p. 391, p. 75.
- Great Basin naturalist memoirs. 1987 [Provo, Utah]Brigham Young University, 1976-1992. url p. 171, p. 79.
- Ground beetles (Carabidae) of Fennoscandia: a zoogeographic study / by Carl H. Lindroth; Joachim Adis, scientific editor. Washington, D.C.: Smithsonian Institution Libraries and National Science Foundation, 1989- url p. 119, p. 476.
- Growth of plants; twenty years' research at Boyce Thompson Institute. New York, Reinhold Pub. Corp., 1948. url p. 40.
- Handbook of flower pollination based upon Hermann Müller's work 'The fertilisation of flowers by insects'; tr. by J.R. Ainsworth Davis. Oxford, Clarendon Press, 1906. url , p. 641, p. 651, p. 93, p. viii.
- Handbook of flower pollination: based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' / Oxford: Clarendon Press, 1906-09. url , , , , , .
- Harper's guide to wild flowers, by Mrs. Caroline A. Creevey. New York, Harper, 1912. url p. 486.
- How to keep bees for profit, New York, The Macmillan company, 1918. url p. 310, p. 321.
- How to make a country place; an account of the successes and the mistakes of an amateur in thirty-five years of farming, building and development: together with a practical plan for securing a home and an independent income, star New York, Orange Judd company; [etc., etc.]1914. url p. 367.
- Hutchison, M. 1992. Vegetation management guideline: Canada thistle (Cirsium arvense (L.) Scop.). Natural Areas Journal 12(3):160-161.
- Hydrochemical, vegetational and microbiological effects of a natural and a constructed wetland on the control of acid mine drainage / Bozeman, Mont.?: Montana State Univ.?, 1988 url .
- Illinois Natural History Survey bulletin. Champaign, Ill.: The Survey, 1987- url p. 295.
- Illinois River Bluffs area assessment / Illinois Department of Natural Resources, Office of Scientific Research and Analysis, [and the] State Geological Survey Division. Springfield, Ill.: Illinois Dept. of Natural Resources, 1998- url p. 157, p. 178.
- Illinois agronomy handbook, 1995-1996. Urbana, Ill.: University of Illinois at Urbana-Champaign, College of Agriculture, Cooperative Extension Service,  url p. 157.
- Integrated pest management in Montana schools training: a study manual for IPM in Montana school pest applicators. Helena, Montana: The Dept., 1996. url p. 76.
- International catalogue of scientific literature. London: Published for the International Council by the Royal Society of London, 1902-1919. url p. 136, p. 249, p. 252, p. 460, p. 549.
- Inventory of plants, plant communities and herpetofauna of concern in the vicinity of the Snow-Talon burn, Helena National Forest / Helena, Mont.: Montana Natural Heritage Program, c2005. url .
- Journal of economic entomology. [College Park, Md., etc.]Entomological Society of America [etc.] url p. 226, p. 479.
- Journal of ethnobiology. 18 1998 Flagstaff, Ariz.: Center for Western Studies, 1981- url p. 74, p. 83, p. 99.
- Journal of the New York Botanical Garden. 16 1915 Lancaster, Pa.: Published for the Garden by the New Era Printing Co., 1900- url p. 229.
- Lake Maxinkuckee. A physical and biological survey by Barton Warren Evermann and Howard Walton Clark. [Indianapolis]Dept. of Conservation, State of Indiana [Wm. B. Burford, printer]1920. url p. 447.
- Lake Maxinkuckee. a physical and biological survey by Barton Warren Evermann and Howard Walton Clark. [Indianapolis, Wm. B. Burford, printer]1920. url p. 447.
- Lake Maxinkuckee: a physical and biological survey / by Barton Warren Evermann and Howard Walton Clark. Indianapolis: Dept. of Conservation, 1920. url p. 447.
- Leaflets of western botany. San Fransisco:[J. T. Howell], 1932-1966. url p. 24, p. 26, p. 293.
- Letters on the diseases of plants. Second series. Published by authority of the government of the state of New South Wales. Sydney, W.A. Gullick, gov't printer, 1904. url , p. 126.
- List of Pteridophyta and Spermatophyta growing without cultivation in northeastern North America. Prepared by a Committee of the Botanical Club, American Association for the Advancement of Science. New York, 1894. url p. 344.
- Lund easement baseline biological inventory / Helena, Mont.: Montana Natural Heritage Program, c2001 url .
- Manual for establishing vegetation on landfills in Ontario / prepared for Ontario Ministry of the Environment; prepared by Gartner Lee Limited. -- [Markham, ON?]: Gartner Lee Ltd., 1990. url .
- Manual of plant diseases, Wilkes-Barré, Pa., The Record press, c1914-22 url p. 375.
- Manual of plant diseases, by Paul Sorauer. Wilkes-Barré, Pa.The Record Press, c1914-22 url p. 375.
- Manual of the southeastern flora: being descriptions of the seed plants growing naturally in Florida, Alabama, Mississippi, eastern Louisiana, Tennessee, North Carolina, South Carolina and Georgia. 1933 New York: The author, 1933. url p. 1481.
- Marcellia. New York [etc.]Pergamon Press [etc.] url , p. 114, p. 125, p. 157, p. 158, p. 26, p. 45.
- Memoirs of the American Entomological Society. Philadelphia, American Entomological Society, 1916- url p. 114, p. 116, p. 117, p. 127, p. 128, p. 134, p. 144.
- Methods in plant histology; by Charles J. Chamberlain. .. Chicago, Ill., The University of Chicago Press[c1915] url p. 267.
- Miscellaneous papers on the botany of Michigan, by C. K. Dodge. Prepared under the direction of Alexander G. Ruthven. Published as a part of the Annual report of the Board of Geological Survey for 1920. Lansing, Mich., Wynkoop Hallenbeck Crawford, State Printers, 1921. url p. 164, p. 221, p. 73.
- Miscellaneous publications / University of Michigan, Museum of Zoology. Ann Arbor, Mich.: The University, 1916- url p. 43.
- Montana gray wolf conservation and management plan: draft environmental impact statement / by Montana Fish, Wildlife and Parks. Helena, Mont.: Montana Fish, Wildlife and Parks, 2003. url p. 275.
- Montana weed management plan / Helena, Mont.: Montana Dept. of Transportation, 2008. url .
- Museum bulletin / Albany, N.Y.: University of the State of New York, 1908-1916. url p. 158, p. 170, p. 248.
- Nantucket wild flowers / by Alice O. Albertson; illustrated by Anne Hinchman. New York and London: G. P. Putnam's sons, 1921. url p. 415, p. 415, p. 429, p. 429.
- National Arboretum contribution. Washington, D.C.: The Arboretum: 1953- url p. 43.
- New York State Museum bulletin. Albany, N.Y.: University of the State of New York, 1916-1944. url p. 110, p. 22, p. 98.
- Notes on the distribution and bibliography of North American bees of the families, Apidae, Meliponidae, Bombidae, Euglossidae, and Anthophoridae, New York1920 url p. 626.
- Oecology of plants: an introduction to the study of plant-communities / by Eug. Warming; assisted by Martin Vahl; prepared for publication in English by Percy Groom and Isaac Bayley Balfour. Oxford: Clarendon Press, 1909. url p. 9, p. 93.
- Oecology of plants; an introduction to the study of plant-communities, by Eug. Warming, assisted by Martin Vahl. Prepared for publication in English by Percy Groom and Isaac Bayley Balfour. Oxford: Clarendon Press, 1909. url p. 9, p. 93.
- On British wild flowers considered in relation to insects / by Lord Avebury. London: Macmillan, 1909. url p. 119.
- Pasture studies: some results, Bangor [Wales]Jarvis & Foster, printers, 1919. url , .
- Physiological plant anatomy, tr. by Montagu Drummond. London, MacMillan, 1914. url p. 525, p. 768.
- Phytologia. Bronx Park, New York, H.A. Gleason and H.N. Moldenke, url p. 222, p. 293, p. 335, p. 394, p. 42, p. 421, p. 424, p. 488, p. 86.
- Plant and animal resources and ecological condition of the Hanging Woman Basin in Big Horn County, Montana and Sheridan County, Wyoming / Helena, Mont.: Montana Natural Heritage Program, c2003. url .
- Plant indicators: the relation of plant communities to process and practice. WashingtonCarnegie Institution of Washington1920 url p. 59.
- Plant life of Alabama, an account of the distribution, modes of association, and adaptations of the flora of Alabama, together with a systematic catalogue of the plants growing in the state. By Charles Mohr. .. Montgomery, Ala., Brown printing co., 1901. url p. 817.
- Plant life of Alabama. An account of the distribution, modes of association, and adaptations of the flora of Alabama, together with a systematic catalogue of the plants growing in the state. Prepared in cooperationwith the Washington, Govt. Print. Off., 1901. url .
- Plant sociology; the study of plant communities; authorized English translation of Pflanzensoziologie, by Dr. J. Braun-Blanquet. Translated, revised and edited by George D. Fuller and Henry S. Conard. New York and London, McGraw-Hill book company, inc., 1932. url p. 291.
- Plant species of concern and plant associations of Powder River county, Montana / Helena, Mont.: Montana Natural Heritage Program, c2002. url .
- Plant species of special concern and plant associations of Sheridan County, Montana / Helena, Mont.: Montana Natural Heritage Program, 2000. url , .
- Principles of animal ecology, by W. C. Allee [and others] Philadelphia, Saunders Co., 1949. url p. 614.
- Proceedings and transactions of the British Entomological and Natural History Society. London, British Entomological and Natural History Society. url , , , , p. 124, p. 38, p. 51, p. 54, p. 56, p. 66, p. 66, p. 73, p. 76, p. 9.
- Proceedings of the Indiana Academy of Science. Indianapolis, Ind.[s.n.] url p. 159, p. 369, p. 369.
- Quality assurance report on exotic plants: EMAP Western Pilot field sites in Montana / Helena, Mont.: Montana Natural Heritage Program, c2001. url .
- Range-wide status assessment of cirsium longistylum (long-styled thistle) / Helena: Montana Natural Heritage Program, c2004. url , , , .
- Rapid ecological assessment of selected state lands in southcentral Montana for plant species of special concern / prepared by James P. Vanderhorst; prepared for Montana Department of Fish, Wildlife and Parks. Helena, MT: Montana Natural Heritage Program,  url p. 10, p. 11, p. 12, p. 15, p. 16, p. 17, p. 18, p. 21, p. 22, p. 28, p. 29, p. 30, p. 7, p. 9.
- Rare plant inventory and plant community descriptions of the Sweet Grass Hills, Proposed Area of Critical Environmental Concern (PACEC), Toole and Liberty Counties, Montana / prepared for United States Department of Interior, Bureau of Land Management; prepared by Western Technology and Engineering, Inc. in cooperation with Montana Natural Heritage Program. Helena, MT: Western Technology and Engineering, Inc.,  url .
- Report of the Michigan Academy of Science. Lansing, Mich.: The Academy, 1904-1916. url p. 131.
- Report of the State Botanist. Albany, N.Y.: University of the State of New York, 1898-1925. url , .
- Report on the conservation status of Cirsium longistylum, a candidate threatened species / Lisa A. Schassberger. Helena, Mont.: Montana Natural Heritage Program, . url p. 10.
- Report. Harpenden [etc.]Lawes Agricultural Trust [etc.] url p. 33, p. 33.
- Rout the weeds! why... when... and how... [by] L. R. Tehon. Urbana, 1937. url p. 15, p. 15, p. 21.
- Rust infection of leaves in petri dishes / [New Haven]: Connecticut Agricultural Experiment Station, 1924. url p. 497, p. 498.
- Sable Island, with a catalogue of its vascular plants / by Harold St. John. Boston: Gray Herbarium of Harvard University, 1921. url p. 44, p. 96.
- Science progress. London: John Murray, 1916- url p. 127.
- Seeds handbook for agriculture, horticulture and forestry, with a key for the identification of the important agricultural seeds = Handbuch der Samenkunde für Landwirtschaft, Gartenbau und Forstwirtschaft, mit einem Schlussel zur Bestimmung der wichtigsten landwirtschaftlichen Samen / Walther Brouwen and Adolf Stahlin. [S.l.: s.n.], 1980. url p. 82.
- Sensitive plant species in weed management areas on the Helena National Forest: final report / Helena, Mont.: Montana Natural Heritage Program, c2002. url .
- Sensitive plant species survey, Ashland District, Custer National Forest, Powder River and Rosebud Counties, Montana / by Bonnie L. Heidel and Hollis Marriott; for Custer National Forest. Helena, MT: Montana Natural Heritage Program,  url , .
- Sensitive plant species survey, Garfield and McCone Counties, Montana / prepared by Bonnie L. Heidel; prepared for Bureau of Land Management. Helena, MT: Montana Natural Heritage Program,  url .
- Sensitive plant survey in the Horse Prairie Creek drainage, Beaverhead County, Montana, Butte District, Bureau of Land Management / prepared by Jim Vanderhorst; prepared for United States Department of Interior, Bureau of Land management, Dillon Resource Area. Helena, Mont.: Montana Natural Heritage Program, c1995. url p. 38.
- Sensitive plant survey in the Sioux District, Custer National Forest, Carter County, Montana, and Harding County, South Dakota / prepared by Bonnie L. Heidel and Keith H. Dueholm; prepared for Custer National Forest. Helena, Mont.: Montana Natural Heritage Program, c1995. url p. 85.
- Sensitive plant survey in the Sweetgrass Hills, Liberty and Toole Counties, Montana / prepared by Bonnie L. Heidel; prepared for Bureau of Land Management. Helena, MT: Montana Natural Heritage Program,  url p. 34, p. 41.
- Sensitive plant survey of the Sage Creek Area, Beaverhead County, Montana, Dillon Resource Area, Bureau of Land Management / prepared by Peter Lesica and Jim Vanderhorst; prepared for USDI Bureau of Land Management, Butte District. Helena, Mt.: Montana Natural Heritage Program,  url p. 34.
- Sensitive plant survey of the Tendoy Mountains, in the Beaverhead National Forest, Beaverhead County, Montana / prepared by Jim Vanderhorst; prepared for United States Forest Service, Beaverhead National Forest. Helena, Mt.: Montana Natural Heritage Program,  url p. 63.
- Sensitive plant surveys in the Big Belt and Elkhorn Mountains, U.S.D.A. Forest Service, Region 1, Helena National Forest, Montana / prepared by Jackie M. Poole and Bonnie L. Heidel; prepared for Helena National Forest. Helena, Mont.: Montana Natural Heritage Program,  url .
- Sensitive plant surveys in the Gallatin National Forest, Montana / prepared by Jim Vanderhorst; prepared for U.S. Forest Service, Gallatin National Forest. Helena, MT: Montana Natural Heritage Program, . url p. 51, p. 53, p. 71.
- Sensitive plant surveys, 1989: U.S. Forest Service, Region 1, Gallatin National Forest / prepared for United States Department of Agriculture, Forest Service; prepared by Sarah Y. Mathews. Helena, Mont.: Montana Natural Heritage Program,  url p. 17.
- Skalkaho timber sale environmental assessment / [Hamilton, Mont.: Southwestern Land Office, DNRC], 2006. url , .
- Special scientific report--wildlife / U.S. Department of the Interior, Fish and Wildlife Service. Washington, D.C.: The Service, 1949- url p. 27, p. 318, p. 363, p. 675.
- Spixiana. 7 1984 München: Zoologische Staatssammlung München, 1977- url p. 149, map 3, p. 98.
- Statewide roadside vegetation management plan: integrated weed management component 2006-2011 / Helena, Mont.: Montana Dept. of Transportation, 2006. url .
- Station bulletin. Durham, N.H.: Agricultural Experiment Station, University of New Hampshire, 1948- url p. 3, p. 3, p. 3, p. 3, p. 5, p. 5, p. 5, p. 5, p. 5, p. 5, p. 96.
- Status review of Cirsium longistylum, U.S.D.A. Forest Service, Region 1 Lewis and Clark National Forest, Montana / Lisa A. Schassberger and Peter L. Achuff. Helena, Mont.: Montana Natural Heritage Program, . url p. 6.
- Survey for Psoralea hypogaea in the Great Falls Resource Area, Lewistown District, Bureau of Land Management, Montana / Helena, Mont.: Montana Natural Heritage Program, c1994. url .
- Swearingen, J. 2009. WeedUS Database of Plants Invading Natural Areas in the United States: Canada Thistle (Cirsium arvense). http://www.invasive.org/weedus/subject.html?sub=2792.
- Syllogeus. Ottawa, National Museum of Natural Sciences, 1972-1995. url p. 22, p. 39.
- Taxonomic and demographic studies of Cirsium longistylum in the Little Belt Mountains, Montana / Lisa Schassberger Roe. Helena, Mont.: Montana Natural Heritage Program,  url p. 1.
- Taxonomic literature: a selective guide to botanical publications and collections with dates, commentaries and types (TL2) Utrecht: Bohn, Scheltema & Holkema, 1976-1988. url p. 733, p. 885.
- Text-book of pastoral and agricultural botany, for the study of the injurious and useful plants of country and farm, by John W. Harshberger. .. with 121 illustrations. Philadelphia: P. Blakiston's Son & Co., [c1920] url p. 252, p. 277.
- Textbook of pastoral and agricultural botany, for the study of the injurious and useful plants of country and farm, by John W. Harshberger. .. with 121 illustrations. Philadelphia, P. Blakiston's Son & Co.[c1920] url p. 252, p. 252, p. 277, p. 277.
- The ABC and XYZ of bee culture; a cyclopedia of everything pertaining to the care of the honey-bee; bees, hives, honey, implements, honey-plants, etc.. .. By A.I. Root and E.R. Root. Medina, Ohio, The A.I. Root Company, 1910. url p. 278.
- The American midland naturalist. Notre Dame, Ind., University of Notre Dame. url p. 172, p. 302, p. 312.
- The Annals of Scottish natural history. Edinburgh: David Douglas, 1892-1911. url p. 221, p. 223.
- The British rust fungi (Uredinales) their biology and classification, Cambridge, University Press, 1913. url .
- The Canadian field-naturalist. 54 1940 Ottawa, Ottawa Field-Naturalists' Club. url polunin , ulke , [fig. 1] , p. 108, p. 110, p. 154, p. 155, p. 159, p. 159, p. 160, p. 162, p. 163, p. 173, p. 174, p. 18, p. 184, p. 185, p. 186, p. 198, p. 207, p. 209, p. 211, p. 213, p. 214, p. 221, p. 223, p. 240, p. 248, p. 251, p. 26, p. 267, p. 284, p. 289, p. 289, p. 290, p. 302, p. 325, p. 34, p. 344, p. 427, p. 43, p. 439, p. 455, p. 456, p. 462, p. 467, p. 497, p. 523, p. 527, p. 53, p. 53, p. 536, p. 537, p. 569, p. 570, p. 577, p. 58, p. 656, p. 68, p. 691, p. 721, p. 721, p. 741, p. 765, p. 89, p. 9, p. 90, p. 91, p. 98.
- The Glasgow naturalist. Glasgow, Andersonian Naturalists of Glasgow. url p. 129, p. 133, p. 30.
- The Great Basin naturalist. 41 1981 Provo, Utah: M.L. Bean Life Science Museum, Brigham Young University, 1939-1999. url p. 21, p. 245, p. 248, p. 252, p. 263, p. 281, p. 424, p. 437, p. 737.
- The Irish naturalist. Dublin: Eason & Son, Ltd., 1892- url p. 210.
- The Journal of agricultural science. Cambridge [Eng.]The University Press. url p. 29.
- The Journal of the College of Science, Imperial University of Tokyo, Japan = Tokyo Teikoku Daigaku kiyo. Rika. Tokyo, Japan: The University, 1898-1925. url p. 46, p. 533.
- The Journal of the Iowa Academy of Science: JIAS. Cedar Falls, Iowa: The Academy, 1988- url p. 226.
- The Macrolepidoptera of the world; a systematic description of the hitherto known Macrolepidoptera, ed. in collaboration with well-known specialists. Stuttgart: Seitz'schen (Kernen), 1906- url p. 19, p. 200, p. 266.
- The Nature Conservancy. Canada Thistle: Element Stewardship Abstract. In: Wildland Weeds Management & Research Program, Weeds on the Web.
- The Ohio journal of science. Columbus, Ohio, The Ohio State University and the Ohio Academy of Science url p. 381, p. 553.
- The Plant world. Baltimore [etc.]Plant World Association [etc.] url p. 156, p. 184.
- The Proceedings and transactions of the Nova Scotian Institute of Science. Halifax, Nova Scotian Institute of Science. url p. 441, p. 81.
- The Review of applied entomology. Farnham Royal, Eng., etc.: Commonwealth Agricultural Bureaux, etc. url p. 290, p. 315, p. 464, p. 536, p. 594, p. 745, p. 758, p. 78, p. 794.
- The Thesis [i.e. Tsesis] oil spill: report of the first year scientific study (October 26, 1977 to December 1978): a cooperative international investigation / by Askö Laboratory, University of Stockholm [and] Swedish Water and Air Pollution Research Institute [and] U.S. Department of Commerce, Office of Marine Pollution Assessment, National Oceanic and Atmo Boulder, Colo.: U.S. Dept. of Commerce, National Oceanic and Atmospheric Administration, Outer Continental Environmental Assessment Program,  url p. 170.
- The University of Kansas science bulletin. 38 1956 [Lawrence]: University of Kansas, 1902-1996. url p. 369, p. 568, p. 568, p. 577, p. 738, fig. 13, page 795.
- The Victoria history of the county of Kent; ed. by William Page. London, Constable, 1908- url p. 159.
- The botany of Bihar and Orissa: an account of all the known indigenous plants of the province and of the most important or most commonly cultivated exotic ones / with maps and introduction by H. H. Haines. London: Printed by Adlard and sold by agents for Indian Official Publications, 1921-25. url p. 1280.
- The botany of Iceland, edited by L. Kolderup Rosenvinge and Eug. Warming. Copenhagen, J. Frimodt, 1912- url p. 296, p. 302.
- The drug plants of Illinois / Leo R. Tehon; drawings by Kay H. Wadsworth. Urbana, Ill.: Natural History Survey Division, 1951. url p. 125.
- The elements of structural botany with special reference to the study of Canadian plants. .. Toronto, W. J. Gage & Co.[1897?] url .
- The faunal connections between Europe and North America. New York, Wiley url p. 174, p. 178, p. 180, p. 197, p. 198, p. 342.
- The flora of Berkshire; being a topographical and historical account of the flowering plants and ferns found in the county, with short biographical notices of the botanists who have contributed to Berkshire botany during the Oxford, Clarendon Press, 1897. url p. 302, p. 303.
- The flora of Montreal Island by Robert Campbell. S.l.: s.n., 1892? url .
- The flora of the town of Southold, Long Island, and Gardiner's Island / New York: Torrey Botanical Club, 1914? url p. 253.
- The handbook for practical farmers, dealing with the more important aspects of farming in the United States, ed. by Hugh Findlay. .. special chapters dealing with farm problems and practices by practical experts in different parts of the United States. .. New York and London, D. Appleton and company, 1920. url p. 518.
- The native flora of the vicinity of Cold Spring Harbor, L.I., New York. n.p., 1925 url p. 214.
- The natural history of plants, their forms, growth, reproduction, and distribution; Dublin, Blackie & son, limited, 1902. url , .
- The natural history of plants; their forms, growth, reproduction, and distribution. From the German of Anton Kerner von Marilaun, by F.W. Oliver, with the assistance of Marian Busk and Mary F. Ewart. with about 2000 original woodcut illustrations and sixteen plates in colours. London, Blackie, 1896-1897. url p. 506, p. 543, p. 798, p. 938, p. 980.
- The naturalised flora of South Australia / by J.M. Black. Adelaide: J.M. Black, 1909. url p. 186, p. 93.
- The plants of Michigan; simple keys for the identification of the native seed plants of the state, by Henry Allan Gleason. Ann Arbor, G. Wahr, c1918. url p. 118.
- The plants of Prince Edward Island / Ottawa: Research Branch, Agriculture Canada, 1985. url p. 260, p. 32.
- The principles of plant culture; a text for beginners in agriculture and horticulture, by the late E. S. Goff, rev. by J. G. Moore and L. R. Jones. .. New York, The Macmillan company, 1916. url p. 87.
- The standard cyclopedia of horticulture; a discussion, for the amateur, and the professional and commercial grower, of the kinds, characteristics and methods of cultivation of the species of plants grown in the regions of the United States a Illustrated with colored plates, four thousand engravings in the text, and ninety-six full-page cuts. New York, Macmillan, 1919 [c1914] url p. 662.
- The vegetation of the Siberian-Mongolian frontiers (the Sayansk region) [Trondhjem]K. Norske Videnskabers Selskab url , , , , .
- The weed flora of Iowa / [by L. H. Pammel; with the collaboration of Charlotte M. King. .. et al.] Des Moines: Iowa Geological Survey, 1913. url p. 380, p. 494, p. 592, p. 651, p. 712, p. 727, p. 735, p. 736, p. 748, p. 788, p. 796, p. 799, p. 808, p. 819, p. 881.
- The weed flora of Iowa Des Moines, Iowa geological survey, 1913. url , , , , , , , , .
- The weed flora of Iowa. .. Des Moines, Iowa Geological Survey, 1913. url p. 379, p. 494, p. 592, p. 651, p. 727, p. 735, p. 736, p. 748, p. 799, p. 808, p. 819.
- Torreya. Burlington, Vt., Torrey Botanical Club, 1901-1945. url p. 124, p. 147, p. 156, p. 160, p. 169, p. 174, p. 18, p. 224, p. 233, p. 240, p. 253, p. 45, p. 79, p. 86, p. 90.
- Transactions and proceedings of the Royal Society of South Australia (Incorporated). Adelaide: W.C. Rigby, 1912-1937. url p. 329, p. 60.
- Transactions of the British Mycological Society. London: Cambridge University Press, [1897-c1988] url p. 22, p. 368, p. 372, p. 388, p. 94, p. 95.
- Transactions of the Illinois State Academy of Science. Springfield, Ill., Illinois State Academy of Science [etc.] url p. 105, p. 138, p. 170, p. 174, p. 181.
- Transactions of the Kentucky Academy of Science. [Lexington, Ky.]Kentucky Academy of Science, 1923-1997. url p. 4, p. 4, p. 45.
- Transactions of the Sapporo Natural History Society. Sapporo, Japan, Sapporo Natural History Society, Hokkaido Imperial University. url p. 138, p. 138, p. 175, p. 175, p. 180.
- USDA, NRCS. 2009. The PLANTS Database (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
- University of Illinois weed control research report. Urbana, Ill.: Dept. of Agronomy, University of Illinois at Urbana-Champaign, 1987-1997. url , p. 103, p. 118, p. 124, p. 448, p. 71.
- Update to the report on the conservation status of Grindelia howellii, a candidated threatened species / Diane S. Pavek. Helena, Mont.: Montana Natural Heritage Program,  url p. 45, p. 48.
- Vascular plant and sensitive plant species inventory for the highland mountains, Deerlodge National Forest; prepared for Deerlodge National Forest / prepared by Peter Lesica. Helena, Mont.: Montana Natural Heritage Program,  url p. 21, p. 41.
- Vascular plants of the Sangamon River basin; annotated checklist and ecological summary [by] Almut G. Jones and David T. Bell. [Urbana], University of Illinois at Urbana-Champaign, College of Agriculture,  url p. 24.
- Vegetation and flora of the Line Creek Plateau area, Carbon County, Montana / prepared by Peter Lesica and the Montana Natural Heritage Program; prepared for USDA Forest Service, Intermountain Research Station. Helena, MT: Montana Natural Heritage Program,  url p. 18, p. 26.
- Weed control / Berkeley, Calif.: College of Agriculture, University of California, 1936. url .
- Weeds of farm land, by Winifred E. Brenchley. New York, Longmans, Green and co., 1920. url , , p. 163, p. 183, p. 211, p. 23, p. 231, p. 24, p. 36, p. 70, p. 82.
- Weeds of farm land. London, Longmans, 1920. url p. 163, p. 179, p. 183, p. 211, p. 23, p. 231, p. 36, p. 70, p. 82, p. ix.
- Weeds of the North Central States. Urbana, Ill: University of Illinois at Urbana-Champaign, College of Agriculture, Agricultural Experiment Station,  url p. 200, p. 267.
- Weeds of the farm and garden, by L.H. Pammel. .. New York, Orange Judd, 1912. url , , p. 33, p. 43.
- Wild flowers east of the Rockies / by Chester A. Reed. New York: Doubleday, Page, 1910. url p. 388, p. 389, p. 412.
- Wild flowers east of the Rockies. Worcester, Mass., Reed, 1910. url p. 388, p. 389, p. 412.
- Wild flowers every child should know: arranged according to color with reliable descriptions of the more common species of the United States and Canada / by Frederic William Stack. New York: Doubleday, Page and Company, 1909. url p. 388, p. 397.
- Woodhawk botanical survey, Fergus County, Montana, Lewistown District of the Bureau of Land Management / Helena, Mont.: Montana Natural Heritage Program, c1997. url .
- Yearbook of agriculture. WashingtonU.S. Govt. Print. Off. url p. 213.
- [Miscellaneous reprints on botany] London, 19 ? url .
- Hsi, Y.-T. 1960. Taxonomy, Distribution and Relationships of the Species of Cirsium Belonging to the Series Undulata. Ph.D. dissertation. University of Minnesota.
- Kelch, D. G. and B. G. Baldwin. 2003. Phylogeny and ecological radiation of New World thistles (Cirsium, Cardueae-Compositae) based on ITS and ETS rDNA sequence data. Molec. Ecol. 12: 141-151.
- Moore, R. J. and C. Frankton. 1969. Cytotaxonomy of some Cirsium species of the eastern United States, with a key to eastern species. Canad. J. Bot. 47: 1257-1275.
- Petrak, F. 1917. Die nordamerikanischen Arten der Gattung Cirsium. Beih. Bot. Centralbl. 35(2): 223-567.
- Brands, S.J. (comp.) 1989-present. The Taxonomicon. Universal Taxonomic Services, Zwaag, The Netherlands. Accessed January 10, 2012.
Accessed through GBIF Data Portal November 18, 2007:
- Jyväskylä University Museum - The Section of Natural Sciences, Vascular plant collection of Jyvaskyla University Museum
- Marine Science Institute, UCSB, Paleobiology Database
- Missouri Botanical Garden, Missouri Botanical Garden
- Oregon State University, Vascular Plant Collection
- The Danish Biodiversity Information Facility, Botany registration database by Danish botanists
- The Swedish Museum of Natural History
- , Herbarium of Oskarshamn
- The Swedish Museum of Natural History
- , Lund Botanical Museum
- The Swedish Museum of Natural History
- , Plants
- UK National Biodiversity Network, Botanical Society of the British Isles - Vascular Plants Database
- UK National Biodiversity Network, Environment and Heritage Service - EHS Species Datasets
- UK National Biodiversity Network, Joint Nature Conservation Committee - Vegetation surveys of coastal shingle in Great Britain
- University of Alaska Museum of the North, University of Alaska Museum of the North Herbarium
- University of Washington Burke Museum, Vascular Plant Collection - University of Washington Herbarium
- Utah Valley State College
- , Utah Valley State College Herbarium
- Biodiversity Heritage Library NamebankID: 2657795
- Catalogue of Life Accepted Name Code: Ast-244
- Global Biodiversity Information Facility Taxonkey: 5304283
- Globally Unique Identifier: urn:lsid:ipni.org:names:78011-3
- GRIN Nomen Number: 100755
- Integrated Taxonomic Information System (ITIS) Taxonomic Serial Number (TSN): 36335
- Natural Heritage Network Species Identifier: PDAST2E090
- U.S.D.A. Plant Symbol: SEAR12
- Zipcode Zoo Species Identifier: 12785
- Plant Conservation Alliance's Alien Plant Working Group. Least Wanted http://www.nps.gov/plants/alien/fact/ciar1.htm [back]
- David J. Keil "Cirsium". in Flora of North America Vol. 19, 20 and 21 Page 57, 66, 82, 83, 93, 95, 96, 97, 100, 102, 1. Oxford University Press. Online at EFloras.org. [back]
- Mean = 91.180 meters (299.147 feet), Standard Deviation = 168.400 based on 20,000 observations. Altitude information for each observation from British Oceanographic Data Centre. [back]