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Cirsium altissimum

(Roadside Thistle)

Overview

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Interesting Facts

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Common Names

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Common Names in English:

Roadside Thistle, Tall Thistle, Tall Thistle Cirsium Altissimum

Description

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Family Compositae

The largest family of flowering plants , the Compositae (Asteraceae), comprising about 1,100 genera and more than 20,000 species and characterized by many small flowers arranged in a head looking like a single flower and subtended by an involucre of bracts. A head may consist of both ray flowers and disk flowers, as in the sunflower, of disk flowers only, as in the burdock, or of ray flowers only, as in the dandelion.

Genus Cirsium

Annuals , 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 bristly-tipped, faces green and glabrous or densely gray-canescent, usually eglandular . Heads discoid , borne singly, terminal and in distal axils, or in racemiform , spiciform , subcapitate , paniculiform , or corymbiform arrays. ( Peduncles with ± reduced leaflike bracts.) Involucres cylindric to ovoid or spheric, (1-6 ×) 1-8 cm. Phyllaries many in 5-20 series, subequal or weakly to strongly, outer and middle with bases appressed 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 midveins in many species with elongate , glutinous resin gland , usually milky in fresh material but dark brown to black when dry) . Receptacles flat to convex , epaleate, covered with tawny to white bristles or setiform scales . Florets 25-200+; corollas white to pink, red, yellow or purple, ± bilateral , tubes long, slender, distally bent, throats short, abruptly expanded. cylindric, lobes linear ; (filaments distinct ) anther 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 slightly angled ; 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.[1]

Physical Description

Species Cirsium altissimum

Biennials or short-lived monocarpic perennials, (50-) 100-300(-400) cm; taproots and often a cluster of coarse fibrous roots , roots without tuberlike enlargements. Stems single, erect , villous with septate trichomes , sometimes ± glabrate , sometimes distally thinly tomentose ; branches few-many, ascending . Leaves: blades oblanceolate to elliptic or ovate , 10-40 × 1-13 cm, margins flat, finely spiny-toothed and otherwise undivided to coarsely toothed or shallowly pinnatifid , lobes broadly triangular, main spines 1-5 mm, abaxial faces white-tomentose, adaxial faces green, glabrate to villous with septate trichomes; basal usually absent at flowering, winged-petiolate, bases tapered; principal cauline well distributed, gradually reduced, bases narrowed, sometimes weakly clasping ; distal cauline well developed. Heads 1-many, in corymbiform or paniculiform arrays, (± elevated above principal cauline leaves., not subtended by ring of spiny bracts. Peduncles 0-5 cm (leafy-bracted.. Involucres ovoid to broadly cylindric or campanulate , (2-) 2.5-3.5(-4) × (1.5-) 2-3(-4) cm, thinly arachnoid . Phyllaries in 10-20 series, strongly imbricate, greenish with subapical darker central zone, ovate (outer) to lanceolate (inner), abaxial faces with a narrow glutinous ridge (milky when fresh, dark when dry), outer and middle entire, bodies appressed , spines slender, abruptly spreading , 3-4 mm; apices of inner phyllaries spreading, narrow, flattened, entire, spines spreading, slender, 3-4 mm; apices of inner phyllaries spreading, narrow, flattened, ± dilated , ± erose or finely serrulate . Corollas pink to purple (white), 20-35 mm, tubes 10-16 mm, throats 5-12 mm, lobes 5-9 mm. Style tips 4-6 mm. Cypselae tan to dark brown, 4-5.5 mm, apical collars stramineous , 0.5-1 mm; pappi 12-24 mm. 2n = 18. [source]

Plants of Cirsium altissimum ranging from southern Minnesota to Texas often have more deeply divided leaves than do populations in other portions of the species' range . Some botanists (e.g. , R. J. Moore and C. Frankton 1969; D. S. Correll and M. C. Johnston 1970) have treated those plants as C. iowense. Others (e.g., R. E. Brooks 1986; H. A. Gleason and A. Cronquist 1991; G. B . Ownbey and T. Morley 1991) have treated them as C. altissimum. Still others considered them to be derivatives of hybridization between C. altissimum and C. discolor (J. T. Kartesz and C. A. Meacham 1999) and treated them as C. ×iowense. Indeed the existence of these plants blurs the distinction between C. altissimum and C. discolor, and herbarium specimens are often difficult to assign. [source]

Natural hybrids between Cirsium altissimum and C. discolor are well documented (R. A. Davidson 1963; G. B. Ownbey and Hsi Y.-T. 1963; Ownbey 1964; S. Dabydeen 1997). Ownbey and Dabydeen both reported that apparent F1 hybrids between the two species have low seed set in comparison with the parental taxa. W. L. Bloom (1977) reported that the chromosomes of the two species differ by several rearareaments. Dabydeen reported a count of 2n = 19 with multiple meiotic irregularities for an apparent F1 hybrid. However, the presence of numerous individuals and populations seemingly intermediate between C. altissimum and C. discolor indicates that although F1 hybrids have low fertility , long-term processes may have stabilized hybrid derivatives of higher fertility. Ownbey and Hsi reported mitotic counts of 2n = 18 and 20 from a population that they treated as C. altissimum. In their discussion they noted that their plants represented "the segregate called C. iowense" and had been collected a short distance from that taxon™s type locality . R. J. Moore and C. Frankton (1969) reported a chromosome number of 2n = 18 for a plant from Texas that they considered to be C. iowense. Further investigation of morphologic variation , chromosome number, meiotic behavior, and fertility is needed of populations named as C. iowense to determine how those plants should be treated. [source]

Habit: Forb/herb

Flowers: Bloom Period: May, June, July, August, September, October. • Flower Color: lavender, violet

Size/Age/Growth

Size: 36-48" tall.

Habitat

Prairies, woodlands, disturbed sites, often in damp soil; 50-700 m [2].

Typically found at an altitude of 0 to 2,761 meters (0 to 9,058 feet).[3]

Biology

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Reproduction

Duration: Biennial

Growth

Culture: Space 36-48" apart.

Soil: Minimum pH: 6.1 • Maximum pH: 7.8

Sunlight: Sun Exposure: Full Sun .

Moisture: Drought Tolerance: High

Temperature: Cold Hardiness: 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b, 10a, 10b. (map)

Taxonomy

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Synonyms

C. iowense (Pammell) Fernald • Carduus altissimus L. • Carduus altissimus Linnaeus • Cirsium altissimum var. biltmoreanum Petrak

Notes

Name Status: Accepted Name .

Comment: Data Providers: New Zealand Plant Name Database, Govaerts World Compositae Checklist A-G, IPNI, LCR Editor. GCC LSID: urn :lsid:compositae.org:names:47B78530-3A03-4A7F-B1F5-CD2AF75A2442

Last scrutiny: 18-Nov-09

Similar Species

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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)

More Info

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Further Reading

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Notes

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Contributors

Data Sources

Accessed through GBIF Data Portal November 21, 2007:

Identifiers

Footnotes

  1. 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]
  2. "Cirsium altissimum". in Flora of North America Vol. 19, 20 and 21 Page 100, 111, 112. Oxford University Press. Online at EFloras.org. [back]
  3. Mean = 288.650 meters (947.014 feet), Standard Deviation = 190.810 based on 712 observations. Altitude information for each observation from British Oceanographic Data Centre. [back]
Last Revised: 7/15/2012