Cirsium lecontei
Cirsium pulcherrimum
black or Le Conte's thistle, Le Conte's thistle
Wyoming thistle
1–few, erect, distal 1/2 nearly naked, loosely arachnoid;
branches 0–5(–10), stiffly ascending.
1–few, erect or ascending, arachnoid-tomentose or ± glabrate;
branches 0–5+, usually in distal 1/2, ascending.
blades linear to oblong or narrowly elliptic, 15–25 × 1–4 cm, coarsely toothed to shallowly pinnatifid, lobes undivided or coarsely few-toothed, main spines 3–6 mm, abaxial faces often ± glabrate, loosely arachnoid when young, adaxial glabrous or sparingly villous with coarse, multicellular trichomes;
basal sometimes absent at flowering, petiolate;
principal cauline sessile, progressively reduced distally, bases clasping or ± decurrent;
distal cauline few, widely separated, bractlike.
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.
5–30 cm (elevated above cauline leaves, not subtended by ring of involucre-like bracts).
0–15 cm.
broadly cylindric to campanulate, 2.5–4 × 1.5–4 cm, loosely arachnoid, ± glabrate.
ovoid to campanulate, 1.8–2.7 × 1–2 cm, thinly arachnoid-tomentose or glabrate.
pink-purple, 22–45 mm, tubes 10–23 mm, throats 8–14 mm, lobes 7–10 mm;
style tips 4–5 mm.
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.
in 6–10 series, imbricate, ovate or lanceolate (outer) to linear-lanceolate (inner), abaxial faces with prominent glutinous ridge, outer and middle tightly appressed, margins spinulose-serrulate, spines ascending, 0.5–2 mm;
apices of inner flat, linear- acuminate.
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.
borne singly or less commonly 2–5(–10) in open, corymbiform arrays.
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.
light brown, 5–5.75 mm, apical collars paler than body, ca. 0.75 mm;
pappi 20–40 mm.
tan to dark brown, 5–6 mm, apical collars yellow, narrow;
pappi 14–16 mm.
= 28, 32.
= 34.
Cirsium lecontei
Cirsium pulcherrimum
Of conservation concern.
Cirsium lecontei occurs on the southern coastal plain. R. J. Moore and C. Frankton (1969) suggested that it originated as a derivative of ancient hybridization between the ancestors of C. horridulum and C. nuttallii. They further suggested a relationship between C. lecontei and C. grahamii of Arizona and hypothesized an ancient dispersal from the southeastern coastal plain to the western cordillera. Although such relationships are possible, I have seen little support for them in my examination of these taxa. I think it is more likely that C. lecontei, C. horridulum, and C. nuttallii originated from a common stock, and that the resemblances between C. lecontei and C. grahamii are a result of convergence.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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.)
1. Distal leaf face gray- to white-tomentose; cypselae without stramineous apical collar | var. aridum |
1. Distal leaf face usually green, glabrous or ± glabrate, but sometimes persistently tomentose; cypselae often with narrow stramineous apical collar | var. pulcherrimum |
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