Cirsium hookerianum |
Cirsium turneri |
|
---|---|---|
Hooker's thistle, white thistle |
cliff thistle |
|
Habit | Biennials or monocarpic (sometimes polycarpic?) perennials, 20–150 cm; taprooted. | Perennials 15–45 cm; stout, branched caudices. |
Stems | usually 1 and erect, less commonly several and ascending, simple to sparingly short-branched in distal 1/2, variably villous with jointed trichomes, and/or finely arachnoid, or ± glabrate; branches on distal stems 0–many, short, ascending. |
5–30+, horizontal or hanging from cliff sides, thinly appressed gray-tomentose and villous with septate trichomes; branches 0–few, distal, ascending. |
Leaves | blades linear-oblong to elliptic, 5–25 × 1–8 cm, subentire to coarsely dentate or deeply pinnatifid, lobes lance-oblong to broadly triangular, spinulose to spiny-dentate or shallowly lobed, main spines 2–10 mm, abaxial faces usually ± densely gray- or white-tomentose with felted arachnoid trichomes, ± villous to tomentose along major veins with septate trichomes, sometimes glabrous or glabrate, adaxial ± green, glabrous to thinly arachnoid, often ± villous or tomentose with septate trichomes; basal often present at flowering, spiny winged-petiolate or sessile; principal cauline well distributed, proximally winged-petiolate, distally sessile, gradually reduced, bases sometimes short-decurrent; distal ± reduced, often narrower than proximal, sometimes with non-pigmented bases, sometimes pectinately spiny. |
blades oblong-elliptic to oblanceolate, 5–30 × 1–5 cm, shallowly to deeply pinnatifid, lobes spreading, triangular, coarsely dentate or lobed, obtuse to acute, main spines slender, 4–10 mm, abaxial faces green or gray-tomentose, villous with septate trichomes along midveins, ± glabrate, adaxial green and glabrous or thinly tomentose, ± glabrate; basal often present at flowering, spiny winged-petiolate; principal cauline sessile, gradually reduced distally; distal oblong, bases ± clasping, usually less deeply lobed and often spinier than proximal. |
Peduncles | 0–8+ cm. |
0–1 cm. |
Involucres | (green or often purplish), broadly ovoid, 2–3.3 × 1.5–4 cm, loosely to densely villous with septate trichomes to tomentose and/or arachnoid. |
cylindric to narrowly campanulate, 3.5–4.5 × 1.5–2 cm, loosely arachnoid, glabrate, finely short-ciliate. |
Corollas | white, ochroleucous, or occasionally pink, 20–28 mm, tubes 10–13 mm, throats 6.5–9 mm, lobes 5–7 mm; style tips 3–5.5 mm. |
red to reddish purple, 26–27 mm, tubes 3.5–5 mm, throats 7.5–9.5 mm, lobes 12–14 mm; style tips ca. 3 mm. |
Phyllaries | in 4–8 series, imbricate to subequal, bases short-appressed, entire, abaxial faces with or without narrow glutinous ridge, apices stiffly spreading to ascending, linear, long, plane, spines straight, slender, 3–5 mm; apices of inner flexuous, sometimes expanded and erose. |
in 5–6 series, imbricate, linear-lanceolate (outer) to linear (inner), entire, abaxial faces without glutinous ridge, apices red to reddish purple, stiffly ascending, long-acuminate, spines straight, 1–10 mm, ± flattened; apices of inner stramineous to red, straight or flexuous. |
Heads | 1–many, borne singly or crowded in spiciform, racemiform, subcapitate, or sometimes more openly branched corymbiform arrays. |
1–6+, borne singly or in condensed corymbiform arrays. |
Cypselae | dark brown, 5–6.5 mm, apical collars not differentiated; pappi 18–22 mm. |
stramineous, 5–6 mm, apical collars not differentiated; pappi 20–25 mm. |
2n | = 34. |
|
Cirsium hookerianum |
Cirsium turneri |
|
Phenology | Flowering summer (Jun–Sep). | Flowering summer (Jun–Sep). |
Habitat | Moist soil, grasslands, aspen parkland, forest edges and openings, subalpine, alpine meadows | Crevices in limestone or basaltic cliffs |
Elevation | 600–2900 m (2000–9500 ft) | 900–1500 m (3000–4900 ft) |
Distribution |
ID; MT; WA; WY; AB; BC
|
TX; Mexico (Chihuahua, Coahuila) |
Discussion | Cirsium hookerianum occurs from the Canadian Coast Ranges of British Columbia east to the northern Cascade Range and the northern Rocky Mountains. The relationship between C. hookerianum, C. kelseyi, which I have tentatively included in C. hookerianum, and C. longistylum needs further investigation. A case could be made for including all three in an expanded concept of C. hookerianum, but more investigation of the variation patterns is needed before this is done. Certainly C. kelseyi is better treated within or as a close ally of C. hookerianum than in C. scariosum (var. scariosum), where R. J. Moore and C. Frankton (1974) synonymized it. Cirsium hookerianum is known to hybridize with C. undulatum. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Cirsium turneri is known from the mountains of the Big Bend area of trans-Pecos Texas and adjacent areas of northern Mexico. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 19, p. 148. | FNA vol. 19, p. 144. |
Parent taxa | Asteraceae > tribe Cardueae > Cirsium | Asteraceae > tribe Cardueae > Cirsium |
Sibling taxa | ||
Synonyms | C. kelseyi | |
Name authority | Nuttall: Trans. Amer. Philos. Soc., n. s. 7: 418. (1841) | Warnock: SouthW. Naturalist 5: 101. (1960) |
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