Cirsium occidentale

(Nuttall) Jepson

Fl. W. Calif., 509. 1901.

Common names: Western thistle
IllustratedEndemic
Basionym: Carduus occidentalis Nuttall Trans. Amer. Philos. Soc., n. s. 7: 418. 1841
Treatment appears in FNA Volume 19. Treatment on page 137. Mentioned on page 101, 102, 104, 105, 140, 1.

Biennials, 5–400 cm; taproots. Stems usually 1, thinly to densely gray or white-tomentose, sometimes ± glabrate; branches few–many, usually from above mid or near base in compact, moundlike dwarf plants, ascending to spreading. Leaves: blades oblong–elliptic to oblanceolate, 6–40 × 1.5–10+ cm, shallowly to deeply pinnatifid, lobes usually rigidly spreading, undivided or with 1–2 pairs of coarse teeth or lobes, main spines 5–15 mm, both faces gray to white-tomentose, sometimes ± glabrate or adaxial faces green, thinly arachnoid-tomentose; basal sometimes present at flowering, petiolate or sessile and bases tapered, spiny-winged; principal cauline much reduced distally, sessile, bases decurrent or not, as spiny wings; distal much reduced, linear, ± bractlike. Heads 1–many in loose to tight clusters (barely raised above rosette in dwarf plants). Peduncles 1–30 cm. Involucres ovoid to spheric, 1.5–5 × 1.5–8 cm, arachnoid to ± loosely tomentose, often adjacent phyllaries connected by conspicuous arachnoid trichomes, sometimes glabrous or glabrate. Phyllaries in 7–10 series, subequal to strongly imbricate, green or stramineous to purple-tinged, linear to narrowly lanceolate, abaxial faces without glutinous ridge; outer and mid bodies appressed, entire, apices deflexed to spreading or ascending, short-triangular to elongate, linear-acicular, spines spreading to reflexed, 1–10+ mm; apices of inner erect, often flexuous, flat. Corollas white to lavender, pink, rose-purple, or red, 18–40 mm, tubes 8–18 mm, throats 5–7 mm, lobes 5–10 mm; style tips 4–5 mm. Cypselae ± brown, 5–6 mm, apical collars not differentiated; pappi 15–30 mm.

Discussion

Varieties 7 (7 in the flora).

Selected References

None.

Key

1 Plants compact, rounded, moundlike; heads usually not much elevated above leaves Cirsium occidentale var. compactum
1 Plants usually erect; principal heads usually conspicuously pedunculate > 2
2 Corollas white to light purple or rose Cirsium occidentale var. californicum
2 Corollas deep purple to bright pink or red > 3
3 Plants densely white-tomentose; phyllaries persistently white-tomentose (except spines); outer phyllaries usually very long, spreading to reflexed Cirsium occidentale var. candidissimum
3 Plants variably tomentose, sometimes ± glabrate; phyllaries ± arachnoid to floccose-tomentose, sometimes green and glabrate; outer phyllaries short to long, ascending to spreading or reflexed > 4
4 Involucres usually about as long as wide or wider than long; phyllaries densely and persistently arachnoid with fine trichomes connecting tips of adjacent phyllaries > 5
4 Involucres usually longer than wide; phyllaries tomentose or glabrate, sparingly or not arachnoid with fine trichomes connecting tips of adjacent phyllaries > 6
5 Phyllary apices ± imbricate, the proximal usually shorter than medial and distal, lanceolate to linear-acicular, 0.5–15 mm; co- rollas bright purple Cirsium occidentale var. occidentale
5 Phyllary apices subequal, all long- acicular, 1.5–3 cm; corollas light to deep reddish purple Cirsium occidentale var. coulteri
6 Corollas 20–24 mm, deep reddish purple; s Santa Lucia Mountains of San Luis Obispo County, California Cirsium occidentale var. lucianum
6 Corollas 23–35 mm, bright pink to red; widespread Cirsium occidentale var. venustum

"fine" is not a number.

... more about "Cirsium occidentale"
arachnoid-tomentose +
short-tailed +
spineless +  and twisted +
dentate +, entire +  and spine-tipped +
deflexed +  and spreading or ascending +
innermost +
scarious +
not differentiated +
corymbiform +, paniculiform +, subcapitate +, spiciform +  and racemiform +
indeterminate +  and determinate +
David J. Keil +
(Nuttall) Jepson +
sessile +  and petiolate +
spiny-winged +
not +, decurrent +  and tapered +
Carduus occidentalis +
compound +  and simple +
6 cm60 mm <br />0.06 m <br /> (40 cm400 mm <br />0.4 m <br />) +
pinnatifid;oblong-elliptic;oblanceolate +
1.5cm;10cm +
10-nerved or 20-nerved +  and rugose +
ascending;spreading +
tawny +  and white +
Western thistle +
actinomorphic +
white +  and lavender pink rose-purple or red +
1.8 cm18 mm <br />0.018 m <br /> (4 cm40 mm <br />0.04 m <br />) +
compressed +  and ovoid +
fertile +  and bisexual +
Calif. +, Nev. +  and Oreg. +
glabrate +  and white-tomentose +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
indeterminate +
each +  and sessile +
1.5 cm15 mm <br />0.015 m <br /> (5 cm50 mm <br />0.05 m <br />) +
arachnoid +  and more or less loosely tomentose +
ovoid;spheric +
1.5 cm15 mm <br />0.015 m <br /> (8 cm80 mm <br />0.08 m <br />) +
sessile +  and petiolate +
cauline +  and basal +
bristle-tipped +
with 1-2 pairs +  and undivided +
deltate +, usually narrowly triangular +  and more or less linear +
0.5 cm5 mm <br />0.005 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
entire +  and dentate +
usually lobed +  and dissected +
2-carpellate +
persistent +
1.5 cm15 mm <br />0.015 m <br /> (3 cm30 mm <br />0.03 m <br />) +
1 cm10 mm <br />0.01 m <br /> (30 cm300 mm <br />0.3 m <br />) +
imbricate +  and adjacent +
middle +  and outer +
glabrate +  and glabrous +
papillate +  and smooth +
Fl. W. Calif., +
bearing subulate enations +, hairy +  and bristly +
flat;convex +
glutinous +
tawny;white +
setiform +  and plumose +
exalbuminous +
subequal +
Illustrated +  and Endemic +
spreading +  and reflexed +
0.1 cm1 mm <br />0.001 m <br /> (1 cm10 mm <br />0.01 m <br />) +
spiny-winged +, simple +  and branched +
appendaged +  and truncate +
dilated +  and swollen +
enlarged +
0.4 cm4 mm <br />0.004 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
Compositae +
Cirsium occidentale +
species +
cylindric +
expanded +
0.5 cm5 mm <br />0.005 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
bristly-dentate to coarsely +
slender +
0.8 cm8 mm <br />0.008 m <br /> (1.8 cm18 mm <br />0.018 m <br />) +
5 cm50 mm <br />0.05 m <br /> (400 cm4,000 mm <br />4 m <br />) +
tree +, vine +, shrub +  and subshrub +