Cirsium pumilum
Cirsium crassicaule
pasture thistle
slough thistle
erect, villous with septate trichomes and sometimes thinly arachnoid tomentose;
branches 0–few, distal, 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 oblong-elliptic, 5–30+ × 2–10 cm, ± undulate, shallowly to deeply pinnatifid, lobes ovate to broadly triangular, usually separated by broad sinuses, spinose-dentate or lobed, main spines 1.5–7 mm, slender to stout, abaxial faces villous with septate trichomes, at least along veins, sometimes thinly arachnoid, adaxial faces villous with septate trichomes and thinly arachnoid tomentose or subglabrous;
basal often present at flowering, bases tapered;
principal cauline sessile, moderately reduced distally, bases often auriculate-clasping;
distal reduced, similar to proximal.
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.
0–15+ cm (above distal leaves), leafy-bracted.
0–15 cm.
broadly cylindric to ovoid, 3.5–5 cm, 2.5–3 cm diam. (appearing much wider and hemispheric to campanulate in pressed specimens), loosely arachnoid on phyllary margins or glabrate.
ovoid to campanulate, 1.5–3 × 1.5–3 cm, ± glabrous.
pink to purple (white), 40–60 mm, tubes 20–35 mm, throats 11–15 mm, lobes 7–10 mm;
style tips 3–7 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 8–10 series, imbricate, ovate or lanceolate (outer) to lance-linear (inner), abaxial faces with ± prominent glutinous ridge, outer and middle appressed, apices ascending to spreading, spines 1.5–6 mm;
apices of middle and inner narrowed and scabrid-denticulate, innermost spineless, tapered and entire or with expanded, erose-denticulate, flexuous tips.
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.
1–few, borne singly at tips of main stem and branches, often closely subtended by 1–several bracts.
1–several at branch tips, closely subtended by clustered leafy bracts or not, collectively forming open, corymbiform or paniculiform arrays.
stramineous to brown, 3.5–5 mm, apical collars yellow or colored like body;
pappi 35–45 mm.
dark brown, 5–5.5 mm, collars narrow, ± stramineous;
pappi 15–20 mm.
= 30.
= 32.
Cirsium pumilum
Cirsium crassicaule
Varieties 2 (2 in the flora).
Flowers of Cirsium pumilum are reportedly sweetly scented.
(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.)
1. Spines of outer phyllaries stout, 3–6 mm; plants usually with several long branches; leaves usually lobed nearly to the midvein; roots rarely and only slightly tuberous-thickened; cypselae usually 3.5– 4 mm | var. pumilum |
1. Spines of outer phyllaries slender, 1.5–3 mm; plants simple or distally with a few short branches; leaves usually shallowly lobed; roots often tuberous-thickened; cypselae usually 4.5–5 mm | var. hillii |
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