Cirsium remotifolium |
Cirsium quercetorum |
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few-leaf thistle, mountain thistle, Pacific fringe thistle, remote-leaf thistle, weak thistle |
Alameda County thistle, brownie or Alameda County thistle, brownie thistle |
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Habit | Perennials, 20–150 cm, monocarpic; taprooted or polycarpic, perennating by runner roots. | Perennials, subacaulescent and forming compact, rounded mounds, 5–20 cm, or ± erect and to 70(–90) cm; runner roots producing adventitious buds. | ||||||||
Stems | usually 1, erect, finely arachnoid-tomentose, sometimes villous with septate trichomes below nodes; branches 0–10+, slender, usually arising in distal 1/2, ascending. |
1–10+, erect or ascending, glabrous to thinly gray-tomentose, sometimes villous with septate trichomes; branches 0 or few, ascending. |
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Leaves | blades linear-oblong to oblanceolate or elliptic, 7–30 × 1–15 cm, unlobed and spinulose to dentate or shallowly to deeply pinnatifid, lobes well separated, linear to triangular-ovate, dentate to deeply lobed, main spines 2–5 mm, slender, abaxial faces green to gray, thinly to densely arachnoid-tomentose, sometimes glabrate, sometimes villous with septate trichomes along veins, adaxial green, glabrous; basal sometimes present at flowering, sessile or winged-petiolate; principal cauline mostly in proximal 1/2, winged-petiolate or sessile, bases narrowed, sometimes auriculate; distal well separated, progressively reduced, becoming bractlike, often unlobed or less deeply divided than the proximal, sometimes spinier than proximal, bases often distally expanded and auriculate-clasping. |
blades elliptic to obovate, 5–20 × 3–7 cm, strongly undulate, shallowly to deeply pinnatifid with 3–8 pairs of lobes, lobes linear-lanceolate to broadly triangular, (often longer than 2 cm), closely spaced, spreading, spinose-dentate or lobed, main spines slender to stout, 2–15 mm, abaxial faces thinly to densely tomentose, ± villous with septate trichomes along veins, glabrescent or trichomes persistent, adaxial thinly arachnoid-tomentose and soon glabrescent; basal usually present at flowering, petiolate; principal cauline petiolate, progressively reduced distally, bases sometimes decurrent as spiny wings to 1 cm; distal reduced, similar to proximal. |
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Peduncles | (0–)2–15 cm. |
0–10 cm, leafy-bracted. |
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Involucres | ovoid to hemispheric or campanulate, 1.5–2.5 × 1.5–3.5 cm, glabrous to arachnoid-floccose. |
ovoid to hemispheric or broadly campanulate, 2.5–5 (in first-formed heads, often smaller in later heads) × 2.5–6 cm, loosely arachnoid on phyllary margins or glabrate. |
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Corollas | creamy white to purple, 18–28 mm, tubes 7–12 mm, throats 5–12 mm, lobes 3.5–7 mm, style tips 4–6 mm. |
white or pale lavender to purple, 25–35 mm, tubes 10–20 mm, throats 7–10 mm, lobes 5–8 mm; style tips 2.5–4.5 mm. |
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Phyllaries | in 6–8 series, subequal to strongly imbricate, green, linear to obovate (outer) to linear (inner), abaxial faces with inconspicuous glutinous ridge; outer and middle bases appressed, margins entire to spinulose-dentate or broad, scarious, lacerate-dentate, spines absent or ascending to spreading, 1–2 mm; apices of inner sometimes flexuous or reflexed, narrow, flat, entire or expanded, scarious, and lacerate-dentate. |
in 5–10 series, imbricate, ovate or lanceolate (outer) to linear-lanceolate (inner), margins of outer entire, abaxial faces without glutinous ridge; outer and mid appressed, spines erect or ascending, (0–)1–2(–10) mm; apices of mid and inner narrowed and scabrido-denticulate or with expanded, spinuloso-serrate or -dentate tips, spineless or spine-tipped. |
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Heads | few–many, borne singly or in openly branched in corymbiform, racemiform, or paniculiform arrays on main stem and branches, sometimes also in distal axils, not closely subtended by clustered leaf bracts. |
1–few, erect, ± crowded, often closely subtended by distalmost leaves. |
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Cypselae | tan to dark brown, 4.5–5.5 mm, apical collars differentiated or not; pappi 13–23 mm. |
brown, 5–6.5 mm, apical collars colored like body; pappi 20–40 mm. |
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2n | = 32. |
= 32. |
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Cirsium remotifolium |
Cirsium quercetorum |
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Phenology | Flowering spring–summer (Apr–Aug). | |||||||||
Habitat | Usually dry sites, coastal bluffs, grasslands, oak woodlands, coastal scrub | |||||||||
Elevation | 0–400 m (0–1300 ft) | |||||||||
Distribution |
CA; OR; WA
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CA
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Discussion | Varieties 3 (3 in the flora). Cirsium remotifolium occurs from the Coast Ranges and valleys of the Pacific Northwest to the western slopes of the Cascade and Klamath ranges, south in the California North Coast Ranges to the San Francisco Bay region. It is closely related to the C. clavatum complex of the Rocky Mountains region. Both have a similar growth habit and some forms variably express the character of broadly scarious, lacerate-toothed phyllary margins. Gray, in naming Cnicus carlinoides var. americanus, included as syntypes both California and Colorado specimens. F. Petrak (1917) treated both the West Coast plants and those of the Rocky Mountains as Cirsium subsect. Americana, recognizing C. remotifolium with several infraspecific taxa plus two other species, C. callilepis and C. amblylepis from the West Coast, and four additional species from the Rocky Mountains. A. Cronquist (1955) rejected Petrak’s subspecies, treating C. remotifolium in a restricted sense, limited to plants of Washington and Oregon without dilated phyllary tips, and circumscribed C. centaureae broadly to include the Rocky Mountains and West Coast plants with dilated phyllary tips. Because of the frequent presence of dilated phyllary tips in C. remotifolium in the restricted sense, Cronquist acknowledged the likelihood of past introgression with C. centaureae in the broad sense. J. T. Howell (1960b) recognized three species: Cirsium remotifolium, C. acanthodontum, and C. callilepis, the latter with four varieties collectively corresponding to the West Coast representatives of C. centaureae (in the sense of Cronquist). Because of the great similarity of the various West Coast plants and their intergradation, I see no value in recognizing two or more species. The West Coast and Rocky Mountains plants are clearly related, but are separated by the Great Basin region and there is little chance of current genetic interchange. As is often the case with American Cirsium, genetic enrichment from past hybridization with other nearby species within their respective areas has likely been fertile ground for evolutionary diversification. Different species have contributed genes in the Pacific states and in the Rockies. I have chosen to recognize two geographically-based species complexes, each with intergrading races here treated as varieties. I treat the West Coast plants as C. remotifolium and the Rocky Mountains plants as C. clavatum. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Cirsium quercetorum occurs in the north and south Coast ranges of California from Mendocino to San Luis Obispo counties. It overlaps in range and habitat with several other thistle species and has been reported to hybridize with C. andrewsii, C. douglasii, C. occidentale, C. remotifolium var. odontolepis, and C. fontinale var. fontinale (F. Petrak 1917; J. T. Howell 1960b). Considerable variation occurs within the range of C. quercetorum, and two of the variants have been given taxonomic recognition as vars. walkerianum and xerolepis. Additional study over the range of the species is needed to determine whether these or other variants should be recognized formally. Cirsium quercetorum appears to be related to the polymorphic C. scariosum complex. The perennial habit with runner roots of C. quercetorum consistently distinguishes it from the monocarpic C. scariosum. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 19, p. 129. | FNA vol. 19, p. 160. | ||||||||
Parent taxa | Asteraceae > tribe Cardueae > Cirsium | Asteraceae > tribe Cardueae > Cirsium | ||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Synonyms | Carduus remotifolius | Cnicus quercetorum, C. quercetorum var. walkerianum, C. quercetorum var. xerolepis, C. walkerianum | ||||||||
Name authority | (Hooker) de Candolle: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 6: 655. (1838) | (A. Gray) Jepson: Fl. W. Calif., 507. (1901) | ||||||||
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