Cirsium lecontei
Cirsium crassicaule
black or Le Conte's thistle, Le Conte's thistle
slough thistle
1–few, erect, distal 1/2 nearly naked, loosely arachnoid;
branches 0–5(–10), stiffly ascending.
usually 1, erect, stout, (hollow, 2–10 cm diam. at base), openly branched distally, thinly arachnoid, villous with jointed trichomes, at least proximally.
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 elliptic to broadly oblanceolate, 15–70 × 30–150+ cm, flat, pinnatifid 1/2–2/3 distance to midvein, larger usually with broad sinuses, lobes broad, few lobed or dentate, main spines 3–8 mm, abaxial faces gray-tomentose, adaxial thinly arachnoid-tomentose, sometimes midveins with jointed trichomes;
basal present or withered at flowering, winged-petiolate;
principal cauline sessile, progressively reduced distally, bases clasping or short-decurrent 1–2 cm;
distal cauline reduced, becoming bractlike, sometimes spinier than proximal.
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, 1.5–3 × 1.5–3 cm, ± glabrous.
pink-purple, 22–45 mm, tubes 10–23 mm, throats 8–14 mm, lobes 7–10 mm;
style tips 4–5 mm.
pale rose-purple (white), 19–26 mm, tubes 9–12 mm, throats 4–6 mm, lobes 5–9 mm;
style tips 3.5–4.5 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 5–7 series, weakly unequal, dark green to brownish, lanceolate (outer) to linear (inner), abaxial faces without (or with very obscure) glutinous ridge;
outer and middle appressed or apices spreading, at least outer irregularly spiny-fringed, finely serrulate, spines slender, 3–5 mm;
apices of inner erect, abaxial faces gray-tomentose, ± twisted.
borne singly or less commonly 2–5(–10) in open, corymbiform arrays.
1–several at branch tips, closely subtended by clustered leafy bracts or not, collectively forming open, corymbiform or paniculiform arrays.
light brown, 5–5.75 mm, apical collars paler than body, ca. 0.75 mm;
pappi 20–40 mm.
dark brown, 5–5.5 mm, collars narrow, ± stramineous;
pappi 15–20 mm.
= 28, 32.
= 32.
Cirsium lecontei
Cirsium crassicaule
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.)
Cirsium crassicaule is known only from a few sites in the San Joaquin Valley. Some populations are threatened by habitat modification and development pressures.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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