Cirsium pulcherrimum |
Cirsium nuttallii |
|||||
---|---|---|---|---|---|---|
Wyoming thistle |
Nuttall's thistle |
|||||
Habit | Perennials polycarpic, 15–60(–90) cm; deep-seated woody tap-roots and caudices. | Biennials, 20–350 cm; taprooted. | ||||
Stems | 1–few, erect or ascending, arachnoid-tomentose or ± glabrate; branches 0–5+, usually in distal 1/2, ascending. |
usually single, erect, glabrous or villous with septate trichomes; branches few–many, ascending. |
||||
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 narrowly to broadly elliptic, (10–)15–60 × (2–)5–15 cm, thin, ± flexible, deeply pinnatifid, lobes narrow, spreading, coarsely dentate or lobed, main spines 2–5 mm, abaxial faces thinly tomentose but often wholly glabrate in age, adaxial glabrous or sparsely villous with septate trichomes; basal often absent at flowering, petioles slender, winged, bases tapered; principal cauline becoming sessile and gradually reduced distally, bases spiny-lobed, sometimes decurrent; distal reduced to linear bracts. |
||||
Peduncles | 0–15 cm. |
1–15 cm, essentially naked (not overtopped by crowded distal leaves). |
||||
Involucres | ovoid to campanulate, 1.8–2.7 × 1–2 cm, thinly arachnoid-tomentose or glabrate. |
hemispheric to campanulate, 1.5–2.5 × 1–2.5 cm, thinly arachnoid or glabrate. |
||||
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. |
white to pink, lavender, or purple, 17–25 mm, tubes 5–11 mm, throats 4–7 mm (noticeably wider than tubes), lobes 5–7 mm; style tips 3–4.5 mm. |
||||
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 6–10 series, strongly imbricate, green or brownish, ovate or elliptic (outer) to linear-lanceolate (inner), abaxial faces with narrow glutinous ridge; outer and middle appressed, bodies entire, spines abruptly spreading, slender, 1–2(–3) mm; apices of inner often flexuous, flat, attenuate. |
||||
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. |
few–many, in open corymbiform or paniculiform arrays. |
||||
Cypselae | tan to dark brown, 5–6 mm, apical collars yellow, narrow; pappi 14–16 mm. |
dark brown, 3–4 mm, apical collars stramineous, 0.5 mm; pappi 17–21 mm (longer bristles shorter than corollas). |
||||
2n | = 34. |
= 24, 26, 28. |
||||
Cirsium pulcherrimum |
Cirsium nuttallii |
|||||
Phenology | Flowering summer (Jun–Aug). | |||||
Habitat | Roadsides, ditches, woodlands, usually in damp soil | |||||
Elevation | 0–100 m (0–300 ft) | |||||
Distribution |
CO; ID; MT; NE; UT; WY
|
AL; FL; GA; LA; MS; NC; SC; TX; VA
|
||||
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.) |
Cirsium nuttallii occurs on the southern coastal plain from southeastern Virginia to southern Florida and west to eastern Louisiana. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
||||
Key |
|
|||||
Source | FNA vol. 19, p. 125. | FNA vol. 19, p. 119. | ||||
Parent taxa | Asteraceae > tribe Cardueae > Cirsium | Asteraceae > tribe Cardueae > Cirsium | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Carduus pulcherrimus | Carduus glaber, Carduus nuttallii | ||||
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: 651. (1838) | ||||
Web links |