Cirsium praeteriens
Cirsium pumilum
lost or Palo Alto thistle, lost thistle, Palo Alto thistle
pasture thistle
stout, erect, loosely arachnoid with fine trichomes and villous with jointed trichomes; branching unknown.
erect, villous with septate trichomes and sometimes thinly arachnoid tomentose;
branches 0–few, distal, ascending.
blades elliptic to oblanceolate, 15–30+ × 6–8+ cm, divided halfway or more to midveins, lobes linear-lanceolate, rigidly spreading, entire or trifid, acuminate, main spines stout, 5–15 mm, abaxial faces tomentose with fine, non-septate trichomes, villous along major veins with septate trichomes, adaxial glabrescent or sparsely tomentose, villous along veins;
basal not observed;
cauline well distributed, distally not much reduced, sessile, bases clasping, not decurrent.
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.
0–1 cm.
0–15+ cm (above distal leaves), leafy-bracted.
hemispheric to broadly campanulate, 3–4 × 4–5+ cm, arachnoid.
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.
white, 30–33 mm, tubes 16 mm, throats 9–12 mm, lobes 5.5–9 mm;
style tips 6 mm.
pink to purple (white), 40–60 mm, tubes 20–35 mm, throats 11–15 mm, lobes 7–10 mm;
style tips 3–7 mm.
in 6–8 series, narrowly lanceolate to linear, outer subequal, rigidly spreading, spines 5–10 mm, inner ± imbricate, bodies appressed, glutinous ridge absent, apices spreading, margins spinulose or scabrid, apices of mid and inner flattened, spineless, scabrid.
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.
1–5, terminal and in distal axils in spiciform arrays.
1–few, borne singly at tips of main stem and branches, often closely subtended by 1–several bracts.
light brown, 6 mm, collars also light brown, ca. 0.75 mm;
pappi 25–33 mm.
stramineous to brown, 3.5–5 mm, apical collars yellow or colored like body;
pappi 35–45 mm.
= 30.
Cirsium praeteriens
Cirsium pumilum
Of conservation concern.
Cirsium praeteriens is known only from Santa Clara County, where J. W. Congdon collected it in Palo Alto in 1897 and 1901. It is presumed extinct.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Varieties 2 (2 in the flora).
Flowers of Cirsium pumilum are reportedly sweetly scented.
(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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