Cirsium longistylum

R. J. Moore & Frankton

Canad. J. Bot. 41: 1562, plate 1. 1963.

Common names: Long-style thistle
EndemicConservation concern
Treatment appears in FNA Volume 19. Treatment on page 149. Mentioned on page 104.

Perennials monocarpic, 40–150 cm; taprooted. Stems usually 1, erect, less commonly several, ascending, simple to sparingly short-branched in distal 1/2, less commonly openly branched, villous with jointed trichomes; branches on distal stems 0–many, short, ascending. Leaves: blades linear to oblong or elliptic, 10–30+ × 1–10 cm, margins flat to undulate, subentire to coarsely dentate or shallowly to deeply pinnatifid, lobes lance-oblong to broadly triangular, spinulose to spiny-dentate or shallowly lobed, main spines 3–12 mm, abaxial faces green and subglabrous to gray or white-tomentose with felted arachnoid trichomes, ± villous to tomentose along major veins with septate trichomes, rarely glabrous or glabrate, adaxial ± green, glabrous or villous with septate trichomes; basal often present at flowering, spiny winged-petiolate or sessile; principal cauline well distributed, proximally winged-petiolate, distally sessile, gradually reduced, bases sometimes short-decurrent (0–2 cm); distal ± reduced, often narrower than the proximal, sometimes with non-pigmented bases. Heads several–many, erect, usually in racemiform or spiciform arrays, usually closely subtended by clustered ± leafy bracts. Peduncles 0–15+ cm. Involucres (green), broadly ovoid, 1.5–2.5 × 1.5–2.5 cm, loosely villous with septate trichomes, sparingly if at all arachnoid. Phyllaries in 4–8 series, subequal, ± lanceolate, bases appressed, apices ascending, linear to broadly expanded, erose to lacerate or spiny-fringed, spines straight, slender, 2–3 mm, abaxial faces with or without narrow glutinous ridge; apices of inner flexuous, sometimes expanded and erose. Corollas white, ochroleucous, 19–23 mm, tubes 6.5–8.5 mm, throats 7.5–11 mm, lobes 4–5 mm; style tips 4–5.5 mm, conspicuously exserted. Cypselae brown, 5.5–6.5 mm, apical collars not differentiated; pappi 17–20 mm. 2n = 34.


Phenology: Flowering summer (Jun–Aug).
Habitat: Moist soil, roadsides, meadows, forest edges and openings
Elevation: 1500–2400 m

Discussion

Of conservation concern.

Cirsium longistylum is endemic to the Big Belt, Castle, Elkhorn, and Little Belt ranges of west-central Montana. It is highly variable, and several authors have suggested that it has introgressed with one or more other species (R. J. Moore and C. Frankton 1963; J. M. Poole and B. L. Heidel 1993; S. J. Brunsfeld and C. T. Baldwin, unpubl.). It is closely related to C. hookerianum, and the two probably share a common ancestry or a history of hybrid interactions dating back to the Pleistocene. Cirsium longistylum is perhaps also affected by modern or historic introgression involving C. scariosum var. scariosum.

Selected References

None.

Lower Taxa

None.

"fine" is not a number."often narrower" is not a number.

... more about "Cirsium longistylum"
gray +  and green +
glabrate +, glabrous +, less villous +  and tomentose +
villous +  and glabrous +
short-tailed +
spiny-fringed +
dentate +, entire +  and spine-tipped +
innermost +
expanded +
scarious +
not differentiated +
spiciform +  and racemiform +
indeterminate +  and determinate +
David J. Keil +
R. J. Moore & Frankton +
sessile +, winged-petiolate +  and spiny +
short-decurrent +
non-pigmented +
decurrent +
Asteraceae tribe Cynareae +
compound +  and simple +
10 cm100 mm <br />0.1 m <br /> (30 cm300 mm <br />0.3 m <br />) +
linear;oblong or elliptic +
1cm;10cm +
10-nerved or 20-nerved +  and rugose +
tawny +  and white +
Long-style thistle +
actinomorphic +
ochroleucous +  and white +
1.9 cm19 mm <br />0.019 m <br /> (2.3 cm23 mm <br />0.023 m <br />) +
compressed +  and ovoid +
fertile +  and bisexual +
1500–2400 m +
gray-canescent +  and glabrous +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Moist soil, roadsides, meadows, forest edges and openings +
indeterminate +
each +  and sessile +
1.5 cm15 mm <br />0.015 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
1.5 cm15 mm <br />0.015 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
sessile +  and petiolate +
cauline +  and basal +
bristle-tipped +
lobed +, spiny-dentate +, lance-oblong +  and broadly triangular +
0.3 cm3 mm <br />0.003 m <br /> (1.2 cm12 mm <br />0.012 m <br />) +
entire +  and dentate +
flat +  and undulate subentire +
2-carpellate +
persistent +
1.7 cm17 mm <br />0.017 m <br /> (2 cm20 mm <br />0.02 m <br />) +
0 cm0 mm <br />0 m <br /> (15 cm150 mm <br />0.15 m <br />) +
Flowering summer (Jun–Aug). +
middle +  and outer +
papillate +  and smooth +
sessile +  and winged-petiolate +
Canad. J. Bot. +
bearing subulate enations +, hairy +  and bristly +
flat;convex +
glutinous +
tawny;white +
setiform +  and plumose +
exalbuminous +
subequal +
Endemic +  and Conservation concern +
straight +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
branched +, simple +  and sparingly short-branched +
ascending +  and erect +
several +  and 1 +
appendaged +  and truncate +
dilated +  and swollen +
enlarged +
0.4 cm4 mm <br />0.004 m <br /> (0.55 cm5.5 mm <br />0.0055 m <br />) +
Compositae +
Cirsium longistylum +
species +
cylindric +
expanded +
0.75 cm7.5 mm <br />0.0075 m <br /> (1.1 cm11 mm <br />0.011 m <br />) +
bristly-dentate to coarsely +
septate +  and jointed +
arachnoid +  and felted +
slender +
0.65 cm6.5 mm <br />0.0065 m <br /> (0.85 cm8.5 mm <br />0.0085 m <br />) +
40 cm400 mm <br />0.4 m <br /> (150 cm1,500 mm <br />1.5 m <br />) +
tree +, vine +, shrub +  and subshrub +