Cirsium brevifolium |
|
---|---|
Palouse thistle |
|
Habit | Perennials, 25–120 cm; taproots with horizontal root sprouts. |
Stems | 1–several, erect, thinly gray-tomentose with fine, non-septate trichomes; branches 0–many, ascending. |
Leaves | oblanceolate or elliptic, 15–45 × 2–10 cm, unlobed and merely spinulose to dentate or deeply pinnatifid, lobes well separated, linear to triangular-ovate, merely spinulose to few toothed or lobed near base, margins often revolute, main spines 2–3(–6) mm, abaxial faces densely gray-tomentose, adaxial green, thinly tomentose or ± glabrate; basal often present at flowering, narrowly winged-petiolate; principal cauline well distributed, gradually reduced distally, bases of proximal cauline winged-petiolate or sessile, bases of distal cauline expanded and ± clasping, margins sometimes spinier than those of proximal; distalmost cauline becoming bractlike, often unlobed or less deeply divided than proximal. |
Peduncles | 1–8 cm. |
Involucres | hemispheric to campanulate, 2.5–3.5 × 2–4 cm, glabrous or loosely floccose. |
Corollas | creamy white, rarely lavender-tinged, 22–28 mm, tubes 8–13 mm, throats 7–11 mm, lobes 4–6 mm; style tips 5–6 mm. |
Phyllaries | in 6–10 series, strongly imbricate, greenish to brown, ovate to lanceolate (outer) to linear (inner), abaxial faces with prominent glutinous ridge; outer and middle appressed, bodies entire, spines abruptly spreading, fine, 2–3(–5) mm; apices of inner commonly flexuous or reflexed, flat, scarious. |
Heads | borne singly and terminal on main stems and branches or few from distal axils in corymbiform or paniculiform arrays. |
Cypselae | brown, 5–6 mm, apical collars yellowish, 0.5–1 mm; pappi 18–22 mm. |
2n | = 22, 26. |
Cirsium brevifolium |
|
Phenology | Flowering summer (Jun–Oct). |
Habitat | Palouse prairie |
Elevation | 600–1300 m (2000–4300 ft) |
Distribution |
ID; OR; WA
|
Discussion | Cirsium brevifolium occurs in the Palouse prairie region of eastern Washington, eastern Oregon, and western Idaho. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 19, p. 124. |
Parent taxa | |
Sibling taxa | |
Synonyms | C. palousense |
Name authority | Nuttall: Trans. Amer. Philos. Soc., n. s. 7: 421. (1841) |
Web links |