Cirsium pulcherrimum |
Cirsium douglasii |
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Wyoming thistle |
Brewer's thistle, California swamp or Douglas' thistle, Douglas' thistle, swamp thistle |
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Habit | Perennials polycarpic, 15–60(–90) cm; deep-seated woody tap-roots and caudices. | Biennials or short-lived monocarpic perennials, 60–250 cm; taprooted. | ||||||||
Stems | 1–few, erect or ascending, arachnoid-tomentose or ± glabrate; branches 0–5+, usually in distal 1/2, ascending. |
1–several, erect or ascending, densely gray-tomentose; branches few–many, ascending to spreading. |
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Leaves | blades linear to oblong, oblanceolate, or elliptic, 5–25 × 0.6–7 cm, unlobed and merely spinulose or spiny-dentate to regularly pinnatifid, lobes 5–8(–many) pairs, well separated, usually with broad, U-shaped sinuses to crowded, linear to triangular-ovate, ascending-spreading to retrorse, merely spinulose to coarsely dentate or few lobed, main spines 2–7 mm, ± slender, abaxial faces gray to white, usually densely arachnoid-tomentose, sometimes ± glabrate, sometimes villous with septate trichomes along veins, adaxial green, glabrous or less commonly thinly to densely gray-tomentose; basal often present at flowering, spiny winged-petiolate; principal cauline well distributed, gradually reduced distally, proximal usually winged-petiolate, mid and distal sessile, bases decurrent as spiny wings 1.5–3.5 cm; distalmost reduced, ± bractlike. |
blades oblong-elliptic to obovate, 10–60 × 2–15 cm, unlobed or shallowly to deeply pinnatifid, lobes lanceolate to ovate-triangular, ascending to spreading, entire to coarsely dentate or lobed, main spines slender to stout, 2–30 mm, faces densely gray-tomentose, rarely glabrate; basal present at flowering, petiolate; principal cauline well distributed, proximal winged-petiolate, distal sessile, bases auriculate-clasping or decurrent as a spiny wing 1–3 cm; distalmost well separated, bractlike. |
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Peduncles | 0–15 cm. |
0–4(–8) cm. |
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Involucres | ovoid to campanulate, 1.8–2.7 × 1–2 cm, thinly arachnoid-tomentose or glabrate. |
ovoid to hemispheric, 1.5–3 cm, 2–4.5 cm diam, loosely arachnoid on phyllary margins or glabrate. |
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Corollas | pink to purple (creamy white), 18–25 mm, tubes 7–9 mm, throats 5.5–7.5 mm, lobes 4–8 mm; style tips 3–5.5 mm. |
rose-purple (white or pinkish-tinged), 18–21 mm, tubes 8–9 mm, throats 5–6 mm (abruptly expanded), lobes 5–6 mm; style tips 3–4.5 mm. |
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Phyllaries | in 6–7 series, ± imbricate, green or with dark subapical patch or appendage, linear to linear-lanceolate, margins entire, abaxial faces with narrow glutinous ridge; outer and middle bases appressed, apical appendages spreading to stiffly ascending, linear-lanceolate to acicular, entire, spines spreading or ascending, stout, 2–7 mm, often flattened; apices of inner stiffly erect or sometimes flexuous, narrow, flat. |
in 6–8 series, imbricate, often with dark purple patch near tip, ovate-lanceolate (outer) to linear-lanceolate (inner), abaxial faces with linear to elliptic glutinous ridge; outer and middle appressed, entire, spines spreading, 1–9 mm; apices of inner often purple-tinged, often flexuous, flattened, spineless, scabrid. |
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Heads | 1–few, borne singly or in 2–3-headed clusters in ± congested flat-topped or racemiform arrays at tips of main stem and branches, sometimes also in distal axils. |
10–many, often crowded at branch tips, collectively forming paniculiform arrays. |
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Cypselae | tan to dark brown, 5–6 mm, apical collars yellow, narrow; pappi 14–16 mm. |
dark brown to black, 5–6 mm, apical collars not differentiated; pappi 15–20 mm. |
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2n | = 34. |
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Cirsium pulcherrimum |
Cirsium douglasii |
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Distribution |
CO; ID; MT; NE; UT; WY
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CA; NV; OR
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Discussion | Varieties 2 (2 in the flora). Cirsium pulcherrimum is closely related to C. clavatum. In southeastern Wyoming and northern Colorado some plants combine foliage and involucral characters of C. pulcherrimum var. pulcherrimum and C. clavatum var. americanum. The inheritance of these characters needs to be examined at the population level to determine whether the intermediates are hybrids or the products of past introgression or incomplete differentiation. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Varieties 2 (2 in the flora). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 19, p. 125. | FNA vol. 19, p. 133. | ||||||||
Parent taxa | Asteraceae > tribe Cardueae > Cirsium | Asteraceae > tribe Cardueae > Cirsium | ||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Synonyms | Carduus pulcherrimus | |||||||||
Name authority | (Rydberg) K. Schumann: Just’s Bot. Jahresber. 29(1): 566. (1903) | de Candolle: in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 6: 643. (1838) | ||||||||
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