Cirsium clavatum var. osterhoutii

(Rydberg) D. J. Keil

Sida 21: 212. 2004.

Common names: Osterhout’s thistle
Endemic
Basionym: Carduus osterhoutii Rydberg Bull. Torrey Bot. Club 32: 131. 1905
Synonyms: Cirsium osterhoutii (Rydberg) Petrak Cirsium araneans Rydberg
Treatment appears in FNA Volume 19. Treatment on page 128. Mentioned on page 127.

Abaxial leaf faces ± tomentose. Involucres ovoid to campanulate, 2–2.8 × 1.5–3 cm, villous-ciliate with long septate trichomes connecting adjacent phyllaries and/or thinly arachnoid-tomentose. Phyllaries in 5–6 series, imbricate or subequal, green or with maroon to dark-brown subapical patch or appendage, linear to linear-lanceolate, abaxial faces with narrow glutinous ridge that often concealed by trichomes; outer and middle bases appressed, apical appendages erect or stiffly ascending, linear-lanceolate to acicular, entire or spinulose-dentate, spines erect or ascending, 2–5 mm; apices of inner sometimes flexuous or reflexed, narrow, flat, and entire or expanded, scarious, and lacerate-dentate.


Phenology: Flowering summer (Jul–Aug).
Habitat: Openings in montane coniferous forests, subalpine, alpine
Elevation: 3000–3600 m

Discussion

The densely pubescent involucre of var. osterhoutii is a feature that links those plants with Cirsium eatonii var. eriocephalum. Some specimens tentatively assigned to C. clavatum var. osterhoutiii may be derivatives of past introgression with C. eatonii var. eriocephalum. Congested heads and strongly undulate leaves with numerous closely spaced lobes are features that suggest such a relationship. Further studies at both population and regional levels are needed to establish the nature of the variation patterns. Where I have observed var. osterhoutii in the field, populations appeared to be morpologically stable, and there was no evidence of current introgression with C. eatonii.

Selected References

None.

Lower Taxa

None.

"fine" is not a number.

green +  and gray +
villous +, glabrate +, glabrous or +  and thinly densely arachnoid-tomentose +
short-tailed +
spineless +  and twisted +
dentate +, entire +  and spine-tipped +
erect +  and spreading +
innermost +
scarious +
spinulose-dentate +  and entire +
ascending +  and erect +
linear-lanceolate +  and acicular +
linear +  and linear-lanceolate +
racemiform +, paniculiform +  and corymbiform +
indeterminate +  and determinate +
David J. Keil +
(Rydberg) D. J. Keil +
petiolate +  and sessile +
lacerate-dentate +  and entire +
decurrent +
Carduus osterhoutii +
compound +  and simple +
5 cm50 mm <br />0.05 m <br /> (40 cm400 mm <br />0.4 m <br />) +
pinnatifid;unlobed;oblong;oblanceolate or elliptic +
3cm;11cm +
10-nerved or 20-nerved +  and rugose +
ascending;arising +
slender +
tawny +  and white +
? (?) +  and ? (?) +
Osterhout’s thistle +
actinomorphic +
creamy white +  and pale pinkish +
1.6 cm16 mm <br />0.016 m <br /> (2 cm20 mm <br />0.02 m <br />) +
tan +  and dark-brown +
compressed +  and ovoid +
fertile +  and bisexual +
3000–3600 m +
gray-canescent +  and glabrous +
linear;linear-lanceolate +
lacerate-dentate +  and entire +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Openings in montane coniferous forests, subalpine, alpine +
clustered +  and or +
indeterminate +
each +  and sessile +
2 cm20 mm <br />0.02 m <br /> (2.8 cm28 mm <br />0.028 m <br />) +
arachnoid-tomentose +
ovoid;campanulate +
1.5 cm15 mm <br />0.015 m <br /> (3 cm30 mm <br />0.03 m <br />) +
sessile +  and petiolate +
cauline +  and basal +
bristle-tipped +
ascending-spreading;retrorse +
linear +  and triangular-ovate +
slender +
0.5 cm5 mm <br />0.005 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
few-lobed +  and dentate +
0.2 cm2 mm <br />0.002 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
entire +  and dentate +
usually lobed +  and dissected +
with maroon to dark-brown subapical patch or appendage +  and green +
linear +  and ovate +
2-carpellate +
persistent +
1.4 cm14 mm <br />0.014 m <br /> (1.6 cm16 mm <br />0.016 m <br />) +
0 cm0 mm <br />0 m <br /> (30 cm300 mm <br />0.3 m <br />) +
Flowering summer (Jul–Aug). +
middle +  and outer +
papillate +  and smooth +
bearing subulate enations +, hairy +  and bristly +
flat;convex +
glutinous +
tawny;white +
setiform +  and plumose +
exalbuminous +
subequal +
ascending +  and erect +
flattened +
0.2 cm2 mm <br />0.002 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
spiny-winged +, simple +  and branched +
ascending +  and erect +
1 +  and several +
appendaged +  and truncate +
dilated +  and swollen +
enlarged +
0.35 cm3.5 mm <br />0.0035 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
maroon +  and dark-brown +
Cirsium osterhoutii +  and Cirsium araneans +
Cirsium clavatum var. osterhoutii +
Cirsium clavatum +
variety +
cylindric +
expanded +
0.4 cm4 mm <br />0.004 m <br /> (0.75 cm7.5 mm <br />0.0075 m <br />) +
bristly-dentate to coarsely +
slender +
0.65 cm6.5 mm <br />0.0065 m <br /> (0.9 cm9 mm <br />0.009 m <br />) +
perennial +  and biennial +
polycarpic +  and monocarpic +
20 cm200 mm <br />0.2 m <br /> (100 cm1,000 mm <br />1 m <br />) +
tree +, vine +, shrub +  and subshrub +
1 cm10 mm <br />0.01 m <br /> (3 cm30 mm <br />0.03 m <br />) +