Cirsium canescens

Nuttall

Trans. Amer. Philos. Soc., n. s. 7: 420. 1841.

Common names: Platte or prairie thistle
Endemic
Synonyms: Cirsium nebraskense (Britton) Lunell Cirsium plattense (Rydberg) Cockerell ex Daniels Cirsium nelsonii (Pammel) Petrak
Treatment appears in FNA Volume 19. Treatment on page 122. Mentioned on page 97, 100, 101, 121, 150, 157.

Biennials or monocarpic perennials, 20–100 cm; taproots long. Stems usually 1, erect, ± densely gray-tomentose with fine, non-septate trichomes; branches 0 or few, usually above middle in distal 1/2, ascending. Leaves: blades oblong to elliptic or obovate, 10–25 (–40) × 2–6 (–12) cm, coarsely dentate or shallowly lobed to deeply pinnatifid, lobes well separated, triangular to linear or oblong, often revolute-margined, ascending to spreading, spinulose to spinose-dentate, main spines 2–3 (–10) mm, faces gray-tomentose, more densely abaxially, sometimes glabrate adaxially; basal usually present at flowering, winged-petiolate; principal cauline progressively reduced distally, bases decurrent as spiny wings 1–5 cm, sometimes with expanded auricles; distal cauline usually much reduced, less lobed. Heads 1–10+, terminal on branches or in distal axils, in openly corymbiform to racemiform arrays. Peduncles 0–10 cm. Involucres hemispheric to broadly campanulate, usually truncate or indented at base, 3–4 × 2.5–4 cm in first-formed heads, often smaller (1.5–2 cm) in later ones, loosely arachnoid on phyllary margins or glabrate. Phyllaries in 6–9 series, imbricate, ovatelanceolate (outer) to linear-lanceolate (inner), abaxial faces with prominent glutinous ridge; bodies of outer and middle appressed, acute, spines ascending to spreading, 2–4 (–8) mm; apices of inner expanded and flat, often twisted, scabrid-margined, and erose, spineless. Corollas dull white or lavender-tinged, 20–35 mm, tubes 10–17 mm, throats 6–11 mm, lobes 4–9 mm; style tips 5–8 mm. Cypselae light-brown, 5–7 mm, sometimes with darker streaks, apical collar very narrow, lighter colored; pappi 18–30 mm, usually noticeably shorter than corolla. 2n = 34, 36.


Phenology: Flowering spring–summer (May–Aug).
Habitat: Sandy or gravelly soils in short-grass prairie, often in disturbed areas, mountain meadows, grassy slopes in montane coniferous forests
Elevation: 1100–3800 m

Distribution

V19-78-distribution-map.gif

Calif., Colo., Mo., Mont., Nebr., Nev., S.Dak., Wyo.

Discussion

Cirsium canescens grows in the northern Great Plains from eastern Montana and Wyoming to eastern Colorado and Nebraska; an upland race occurs in the Rocky Mountains of eastern Colorado. It has been reported from Iowa, North Dakota, and Ohio; I have not seen specimens from those states. It is adventive in northeastern California.

Cirsium canescens hybridizes locally with C. scariosum and C. parryi. Further investigations may reveal that high-elevation forms of C. canescens from the mountains of Colorado are worthy of taxonomic recognition. These plants flower later than the low elevation forms of the Great Plains and occur in rather different ecologic conditions, but I have found no features that readily distinguish them. Populations of C. canescens have been particularly affected by the seedhead weevil Rhinocyllus conicus, introduced to North America to control weedy species of Carduus (S. M. Louda et al. 1997; Louda 1998).

Selected References

None.

Lower Taxa

None.

"fine" is not a number.

... more about "Cirsium canescens"
short-tailed +
spineless +  and twisted +
dentate +, entire +  and spine-tipped +
erect +  and spreading +
innermost +
scarious +
openly corymbiform +  and racemiform +
indeterminate +  and determinate +
expanded +
David J. Keil +
Nuttall +
winged-petiolate +
decurrent +
Asteraceae tribe Cynareae +
compound +  and simple +
25 cm250 mm <br />0.25 m <br /> (40 cm400 mm <br />0.4 m <br />) +
6 cm60 mm <br />0.06 m <br /> (12 cm120 mm <br />0.12 m <br />) +
10 cm100 mm <br />0.1 m <br /> (25 cm250 mm <br />0.25 m <br />) +
shallowly lobed;deeply pinnatifid +
2cm;6cm +
spineless +, scabrid-margined +  and twisted +
10-nerved or 20-nerved +  and rugose +
tawny +  and white +
Platte or prairie thistle +
actinomorphic +
lavender-tinged +, white +  and dull +
2 cm20 mm <br />0.02 m <br /> (3.5 cm35 mm <br />0.035 m <br />) +
compressed +  and ovoid +
fertile +  and bisexual +
Calif. +, Colo. +, Mo. +, Mont. +, Nebr. +, Nev. +, S.Dak. +  and Wyo. +
1100–3800 m +
glabrate +  and gray-tomentose +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Sandy or gravelly soils in short-grass prairie, often in disturbed areas, mountain meadows, grassy slopes in montane coniferous forests +
indeterminate +
each +  and sessile +
3 cm30 mm <br />0.03 m <br /> (4 cm40 mm <br />0.04 m <br />) +
glabrate +  and arachnoid +
hemispheric;broadly campanulate usually truncate or indented +
2.5 cm25 mm <br />0.025 m <br /> (4 cm40 mm <br />0.04 m <br />) +
sessile +  and petiolate +
cauline +  and basal +
revolute-margined +
spinulose +  and spinose-dentate +
ascending;spreading +
triangular +  and linear or oblong +
0.3 cm3 mm <br />0.003 m <br /> (1 cm10 mm <br />0.01 m <br />) +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
entire +  and dentate +
usually lobed +  and dissected +
2-carpellate +
persistent +
usually noticeably shorter +
1.8 cm18 mm <br />0.018 m <br /> (3 cm30 mm <br />0.03 m <br />) +
0 cm0 mm <br />0 m <br /> (10 cm100 mm <br />0.1 m <br />) +
Flowering spring–summer (May–Aug). +
middle +  and outer +
weakly to strongly +
papillate +  and smooth +
Trans. Amer. Philos. Soc., n. s. +
bearing subulate enations +, hairy +  and bristly +
flat;convex +
glutinous +
tawny;white +
setiform +  and plumose +
exalbuminous +
subequal +
0.4 cm4 mm <br />0.004 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
ascending +  and spreading +
0.2 cm2 mm <br />0.002 m <br /> (0.4 cm4 mm <br />0.004 m <br />) +
spiny-winged +, simple +  and branched +
appendaged +  and truncate +
dilated +  and swollen +
enlarged +
0.5 cm5 mm <br />0.005 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
Cirsium nebraskense +, Cirsium plattense +  and Cirsium nelsonii +
Cirsium canescens +
species +
cylindric +
expanded +
0.6 cm6 mm <br />0.006 m <br /> (1.1 cm11 mm <br />0.011 m <br />) +
bristly-dentate to coarsely +
slender +
1 cm10 mm <br />0.01 m <br /> (1.7 cm17 mm <br />0.017 m <br />) +
perennial +  and biennial +
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 /> (5 cm50 mm <br />0.05 m <br />) +