Common Names in English:
Thurber Wire Lettuce, Thurber's Wirelettuce
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.
The Lactuceae are a tribe of closely related genera of the sunflower family that are easily recognized because the flowering heads are composed of wholly of ligulate florets that are usually 5-lobed. Another very distinguishing feature is the milky sap . Although not apparent without magnification, the pollen is distinctive in that the spines are more or less restricted to discrete ridges or flanges on the surface of the grain. In other members of the family the spines are distributed more or less evenly over the surface of the pollen grain . The pappus usually consists of scales or stiff hairs . -- Gerald D. Carr.
, 10-200 cm, taprooted, or perennials
, 10-100 cm. with deeply seated, woody caudices or stout or slender, creeping
rhizomes. Stems (1-8) erect
or branched, usually glabrous
, sometimes hairy
(especially when young). Leaves basal (withered at flowering in annuals and some perennials) and/or cauline (much reduced, bractlike in annuals and some perennials) ; usually sessile; blades
, or spatulate
, usually runcinate, margins
usually pinnately lobed
(spinulose-tipped in S. parryi), sometimes entire or toothed
(S. lactucina, S. tenuifolia, and S. fluminea (faces
, or tomentose
) ; distal bractlike (to 45 mm in S. fluminea). Heads borne singly or clustered (in paniculiform
arrays in some subspecies
of S. exigua). Peduncles not inflated
distally, sometimes bracteate
. Calyculi of 3-5, unequal bractlets
in some perennials; not distinguishable in S. cichoriacea), appressed
(some annuals). Involucres ± cylindric
, 2-3(-5+) mm diam. Phyllaries usually 5-12 in 1 series, equal (20-25 in 2-3 series, unequal in S. cichoriacea, usually glabrous, rarely puberulent, densely stipitate-glandular
in S. exigua subsp.
deanei). Receptacles flat, usually smooth
in S. cichoriacea), glabrous, epaleate. Florets (4-) 5-16; corollas usually pink or lavender, sometimes white (annuals often purple-tinged abaxially). Cypselae light tan to dark brown, columnar
, sometimes slightly curved
, 5-angled, apices truncate
, faces equal, sometimes with ribs
between faces, each face with central, narrow, longitudinal
or furrow (not grooved
in S. virgata), otherwise smooth or bumpy to tuberculate
, usually glabrous (scaberulous in S. fluminea) ; pappi persistent
(or only widened bases
persistent after distal portions break
off) or falling, of 5-40, distinct
or basally connate
in groups, white to tan, wholly or distally plumose bristles in 1 series. x = 8.
Species 16: w North America, n Mexico.
Because all the species of Stephanomeria have not previously been examined at one time, the present treatment provides the first unified picture of their variability, ecologic specializations, and geographic distributions. The genus includes six annual species (all in the flora ) and ten perennial species (eight in the flora, one in the mountains of northern Baja California, and one known only from Guadalupe Island, Mexico).
Taxonomic distinctions among annual species of Stephanomeria did not become evident until their morphology and geographic distributions were correlated with their chromosome numbers and reproductive compatibilities (L. D. Gottlieb 1971, 1972). The same studies also provided an hypothesis that satisfactorily accounted for their variability. Studies showed that S. exigua and S. virgata differed for a relatively large number of characters and that other annual species originated from genetic segregates that were formed by hybridization, at both diploid and tetraploid levels, as well as directly from S. exigua.
Stephanomeria exigua has five subspecies; S. virgata has two. Within each species, the subspecies share numerous morphologic features as well as chromosomal karyotype . They are recognized as polytypic because reproductive compatibility between any pair of subspecies of S. exigua or between subspecies of S. virgata is substantially higher than is the compatibility between the two species. The two species appear to represent a fundamental phylogenetic divergence within annuals; nevertheless their different features are combined in different ways in S. elata and S. diegensis.
Stephanomeria paniculata and S. malheurensis probably evolved more or less directly from S. exigua subsp. coronaria. The speciation process that gave rise to S. malheurensis (L. D. Gottlieb 1978) has been examined in a series of studies (Gottlieb 1973b, 1977, 1979; S. Brauner and Gottlieb 1987, 1989). The origin of the highly self-pollinating S. paniculata may have been similar but much less evidence is available. Stephanomeria malheurensis has served as a model for reintroduction of a species back into its original habitat after local extinction , in its case by competition from invasive cheatgrass (Bromus tectorum).
Information about evolution and speciation is not so available for the perennials as for the annuals. Treatment of perennials is based almost entirely on examination of herbarium specimens plus published information describing their chromosome numbers. Although little is known about phylogenetic relationships among perennial species of Stephanomeria, a recent DNA sequencing study of nuclear rDNA (J. Lee et al. 2002) showed that the genus does not include either Munzothamnus blairii (previously S. blairii) or Pleiacanthus spinosus (previously S. spinosa). Without them, Stephanomeria is a well-supported, monophyletic group of species.
The DNA analysis suggested that Stephanomeria tenuifolia, S. runcinata, S. fluminea, and S. thurberi comprise a subclade. Those four species are perennial and all have fully plumose , white pappus bristles. They differ markedly in their ecologic specializations, as indicated in their treatments below. The DNA studies also showed a very close relationship between S. malheurensis and S. exigua subsp. coronaria consistent with results of previous studies (cited above). It is to be hoped that taxonomic information presented below will make species of Stephanomeria more easily accessible to continuing studies.
Species Stephanomeria thurberi
, 20-50 cm (rhizomes slender). Stems single.
branches on distal 1/3-1/2, glabrous
or sparsely puberulent
green at flowering (at least on plants
and early summer,
frequently absent in plants of late summer) ; basal blades
, runcinate, 4-7 cm, margins
or sparsely puberulent). cauline reduced, scalelike on plants of
spring and early summer, linear
and threadlike (to 3 cm) on plants
of late summer. Heads borne singly on branch
mostly 5-100+ mm (bracteolate
). Calyculi of (4-6) appressed
to 1/2 phyllaries). Involucres
9-11(-12) mm (phyllaries 6-8, glabrous). Florets 10-16(-20).
Cypselae tan, 5-6 mm, faces smooth
of 30-40, white bristles
), wholly plumose
= 16. [source]
Stephanomeria thurberi has been collected most often in May, June, and early July. These specimens have well developed basal rosettes, stems with nodes 3+ cm apart, relatively short branches, usually only on the distal 30-50%, and scalelike, cauline leaves. That is the form described by Gray. Another form has been collected from late July into early September that is morphologically distinct , as first pointed out by A. S. Tomb on the labels of specimens he collected in 1968 and 1970 (see below). That "summer form" lacks basal rosettes, the stems have more numerous nodes, about 1 per cm, beginning at ground level, and threadlike cauline leaves 3-4 cm. Those specimens usually have relatively few heads . Some specimens collected in July are intermediate, having basal rosettes and relatively long, threadlike cauline leaves, or no rosettes and relatively short, scalelike cauline leaves. [source]
It is not known if the different growth forms represent distinct genotypes that initiate growth at different times, or if the same individual produces aboveground parts with differing appearances during the growth season. It is also not known if the two forms commonly grow together as they do in Coconino County, Arizona (Tomb 280, August 10, 1968, and Tomb 631, June 12, 1970), or if they generally occupy different habitats . The unusual situation calls for study. [source]
Flowers: Bloom Period: May, June, July, August, September.
Open, sandy sites in juniper-mesquite grasslands and in yellow pine forests , sometimes growing as weed along roadsides; 1200-2500 m (Ref. 101939).
- Whittaker & Margulis,1978
- Haeckel, 1866
- Cavalier-Smith, 1981
- Sinnott, 1935 ex Cavalier-Smith, 1998
- Vascular Plants
- Brongniart, 1843
- Takhtajan, 1967
- Takhtajan Ex Reveal, 1992
- Lindley, 1833
- Giseke, 1792, nom. cons., nom. alt.
- Nuttall, 1841, nom. cons.
- Stickweed, wirelettuce. skeletonweed [Greek stephanos, crown. wreath, and meris, part, presumably alluding to appearance of plumose bristles of pappus]
- Specific epithet:
- A. Gray, Pl. Nov. Thurb. 325. 1854.
- Botanical name: - Stephanomeria thurberi Gray A. Gray, Pl. Nov. Thurb. 325. 1854.
- Specific epithet: thurberi - A. Gray, Pl. Nov. Thurb. 325. 1854.
- Genus: Stephanomeria () - Nuttall, 1841, nom. cons. - Stickweed, wirelettuce. skeletonweed [Greek stephanos, crown. wreath, and meris, part, presumably alluding to appearance of plumose bristles of pappus]
- Subtribe: Stephanomeriinae ()
- Tribe: Lactuceae ()
- Subfamily: Cichorioideae ()
- Family: Compositae () - Giseke, 1792, nom. cons., nom. alt.
- Order: Asterales () - Lindley, 1833
- Superorder: Campanulanae () - Takhtajan Ex Reveal, 1992
- Subclass: Asteridae () - Takhtajan, 1967
- Class: Spermatopsida () - Brongniart, 1843
- Subphylum: Euphyllophytina ()
- Phylum: Tracheophyta () - Sinnott, 1935 ex Cavalier-Smith, 1998 - Vascular Plants
- Subkingdom: Viridaeplantae () - Cavalier-Smith, 1981
- Kingdom: Plantae () - Haeckel, 1866 - Plants
Lygodesmia thurberi (Gray) Shinners
Name Status: Accepted Name . Latest taxonomic scrutiny: 15-Mar-2000
Members of the genus Stephanomeria
ZipcodeZoo has pages for 27 species, subspecies, varieties, forms, and cultivars in this genus:
S. blairii (Blair's Wirelettuce) · S. cichoriacea (Chicoryleaf Wirelettuce) · S. diegensis (Wreathplant) · S. elata (Santa Barbara Wirelettuce) · S. exigua (Small Wirelettuce) · S. exigua deanei (Deane's Wirelettuce) · S. exigua exigua (Small Wirelettuce) · S. exigua macrocarpa (Small Wirelettuce) · S. lactucina (Creeping Wirelettuce) · S. lygodesmoides (Skeleton Wirelettuce) · S. malheurensis (Malheur Wire Lettuce) · S. minor (Lesser Wirelettuce) · S. minor var. minor (Narrowleaf Wirelettuce) · S. minor var. myrioclada (Narrowleaf Wirelettuce) · S. minor var. uintensis (Uinta Wirelettuce) · S. paniculata (Tufted Wirelettuce) · S. parryi (Parry Wire Lettuce) · S. pauciflora (Brownplume Wirelettuce) · S. pauciflora var. Pauciflora (Wire-Lettuce) · S. runcinata (Desert Wirelettuce) · S. schottii (Schott Wire Lettuce) · S. spinosa (Spiny Skeletonweed) · S. tenuifolia var. tenuifolia (Narrowleaf Wirelettuce) · S. thurberi (Thurber Wire Lettuce) · S. virgata (Rod Wirelettuce) · S. virgata pleurocarpa (Wand Wirelettuce) · S. wrightii (Wright's Wirelettuce)
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- Biologia centrali-americana; or, Contributions to the knowledge of the fauna and flora of Mexico and Central America. London, Pub. for the editors by R. H. Porter and Dulau & co., 1879-88. url .
- Bulletin of the Southern California Academy of Sciences. Los Angeles, Calif.: The Academy, 1902-1971. url p. 36.
- Contributions from the United States National Herbarium 29 1957 Washington, D.C.: Smithsonian Institution Press, 1890- url p. 137, p. 227, p. 620, p. XIII.
- Flora of New Mexico / by E.O. Wooton and Paul C. Standley. Washington: G.P.O., 1915. url p. 620.
- Flora of New Mexico. By E.O. Wooton and Paul C. Standley. WashingtonGovt. Print. Off.1915 url p. 620.
- Gottlieb, L. D. 1971. Evolutionary relationships in the outcrossing diploid annual species of Stephanomeria (Compositae). Evolution 25: 312-329.
- Gottlieb, L. D. 1972. A proposal for classification of the annual species of Stephanomeria (Compositae). Madroño 21: 463-481.
- Bisby, F.A., Y.R. Roskov, M.A. Ruggiero, T.M. Orrell, L.E. Paglinawan, P.W. Brewer, N. Bailly, J. van Hertum, eds (2007). Species 2000 & ITIS Catalogue of Life: 2007 Annual Checklist. Species 2000: Reading, U.K.
- Brands, S.J. (comp.) 1989-present. The Taxonomicon. Universal Taxonomic Services, Zwaag, The Netherlands. Accessed January 12, 2012.
- Global Biodiversity Information Facility. Accessed February 28, 2008. http://www.gbif.org Mediated distribution data from 3 providers.
- "Stephanomeria thurberi". in Flora of North America Vol. 19, 20 and 21 Page 351, 352, 358. Published by Oxford University Press. Online at EFloras.org.
- USDA, NRCS. 2005. The PLANTS Database, Version 3.5 (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.
Accessed through GBIF Data Portal February 28, 2008:
- Arizona State University, International Institute for Species Exploration: Arizona State University Vascular Plant Herbarium
- Arizona State University, International Institute for Species Exploration: The Deaver Herbarium, Northern Arizona University
- Missouri Botanical Garden
- USDA PLANTS: USDA PLANTS Database
- Biodiversity Heritage Library NamebankID: 2659338
- Catalogue of Life Accepted Name Code: ITS-38456
- Globally Unique Identifier: urn:lsid:ipni.org:names:251208-1
- Integrated Taxonomic Information System (ITIS) Taxonomic Serial Number (TSN): 38456
- MoBot NameID: 2711167
- U.S.D.A. Plant Symbol: LYTH4
- Zipcode Zoo Species Identifier: 48660