Cirsium tracyi

(Rydberg) Petrak

Beih. Bot. Centralbl. 35(2): 424. 1917.

Common names: Tracy’s thistle
Endemic
Basionym: Carduus tracyi Rydberg Bull. Torrey Bot. Club 32: 133. 1905
Synonyms: Cirsium acuatum (Osterhout) Cockerell Cirsium floccosum (Rydberg) Petrak Cirsium undulatus var. tracyi (Rydberg) S. L. Welsh
Treatment appears in FNA Volume 19. Treatment on page 121. Mentioned on page 106, 107, 122.

Perennials, 50–200+ cm; taprooted. Stems 1–several, erect or ascending, thinly gray-tomentose or ± glabrate; branches few-to-many, ascending. Leaves: blades elliptic to oblong, 8–40 × 1–12 cm, margins weakly to strongly undulate, spinose-dentate or shallowly to deeply lobed, lobes ascending to spreading, ± triangular, mostly well separated, spinulose and coarsely dentate or cleft into 2–3 lanceolate to triangular, often entire-margined, spine-tipped divisions, main spines 2.5–7+ mm, abaxial faces densely gray-tomentose, adaxial thinly tomentose; basal sometimes present at flowering, winged-petiolate; principal cauline becoming sessile and progressively reduced distally, widest at bases, bases ± auriculate-clasping to short-decurrent; distal cauline reduced, often spinier. Heads 1–many, terminal on branches and often in leaf-axils, in leafy, ± corymbiform arrays. Peduncles 0–10+ cm. Involucres ovoid to hemispheric or broadly campanulate, 2–3 × 1.7–3.5 cm, loosely arachnoid on phyllary margins or glabrate. Phyllaries in 6–10 series, imbricate, ovate to lanceolate (outer) to linear-lanceolate (inner), margins entire, abaxial faces with prominent glutinous ridge; outer and middle appressed, spines spreading, slender to stout, 2–6 mm; apices of inner often flexuous, narrow, flat, ± entire, spineless or tipped with weak spines. Corollas white to lavender or pink-purple, 23–30 mm, tubes 9–14 mm, throats 5.5–10.5 mm, lobes 5.5–9.5 mm; style tips 4–7 mm. Cypselae light to dark-brown, 6–7 mm, apical collars colored like body or rarely yellowish, narrow; pappi 20–23 mm, usually noticeably shorter than corolla. 2n = 24.


Phenology: Flowering late spring–summer (Jun–Aug).
Habitat: Dry slopes, sagebrush deserts, pinyon-juniper woodlands, openings in montane coniferous forests, often in disturbed areas
Elevation: 1400–2900 m

Discussion

Cirsium tracyi occurs from eastern Utah and western Colorado south in the Colorado Plateau and southern Rocky Mountains to northwestern New Mexico. Large-headed plants of Cirsium tracyi and small-headed individuals of C. undulatum are sometimes difficult to distinguish. P. L. Barlow-Irick (unpubl.) found that although there is much overlap in floral measurements of C. tracyi and C. undulatum, the means for some of these characters are statistically significant. Corolla lobes of C. tracyi, for instance, average about 7 mm and those of C. undulatum about 10 mm. The species differ in chromosome number as well.

Selected References

None.

Lower Taxa

None.

"fine" is not a number.

... more about "Cirsium tracyi"
short-tailed +
spineless +  and twisted +
dentate +, entire +  and spine-tipped +
erect +  and spreading +
innermost +
scarious +
yellowish +  and colored +
corymbiform +, paniculiform +, subcapitate +, spiciform +  and racemiform +
indeterminate +  and determinate +
David J. Keil +
(Rydberg) Petrak +
winged-petiolate +
less auriculate-clasping +  and short-decurrent +
decurrent +
Carduus tracyi +
compound +  and simple +
8 cm80 mm <br />0.08 m <br /> (40 cm400 mm <br />0.4 m <br />) +
elliptic;oblong +
1cm;12cm +
10-nerved or 20-nerved +  and rugose +
tawny +  and white +
Tracy’s thistle +
actinomorphic +
white +  and lavender or pink-purple +
2.3 cm23 mm <br />0.023 m <br /> (3 cm30 mm <br />0.03 m <br />) +
light +  and dark-brown +
compressed +  and ovoid +
fertile +  and bisexual +
Colo. +, N.Mex. +  and Utah. +
entire-margined +
lanceolate;triangular +
1400–2900 m +
gray-canescent +  and glabrous +
tipped +, spineless +  and entire +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
Dry slopes, sagebrush deserts, pinyon-juniper woodlands, openings in montane coniferous forests, often in disturbed areas +
indeterminate +
each +  and sessile +
2 cm20 mm <br />0.02 m <br /> (3 cm30 mm <br />0.03 m <br />) +
glabrate +  and arachnoid +
ovoid;hemispheric or broadly campanulate +
1.7 cm17 mm <br />0.017 m <br /> (3.5 cm35 mm <br />0.035 m <br />) +
sessile +  and petiolate +
cauline +  and basal +
bristle-tipped +
cleft +, dentate +  and spinulose +
ascending;spreading +
triangular +
0.25 cm2.5 mm <br />0.0025 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
spinose-dentate or +  and shallowly deeply lobed +
2-carpellate +
persistent +
usually noticeably shorter +
2 cm20 mm <br />0.02 m <br /> (2.3 cm23 mm <br />0.023 m <br />) +
0 cm0 mm <br />0 m <br /> (10 cm100 mm <br />0.1 m <br />) +
Flowering late spring–summer (Jun–Aug). +
middle +  and outer +
weakly to strongly +
papillate +  and smooth +
Beih. Bot. Centralbl. +
bearing subulate enations +, hairy +  and bristly +
flat;convex +
glutinous +
tawny;white +
setiform +  and plumose +
exalbuminous +
subequal +
Slender (?) +  and Stout (?) +
0.2 cm2 mm <br />0.002 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
spiny-winged +, simple +  and branched +
ascending +  and erect +
1 +  and several +
appendaged +  and truncate +
dilated +  and swollen +
enlarged +
0.4 cm4 mm <br />0.004 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
Cirsium acuatum +, Cirsium floccosum +  and Cirsium undulatus var. tracyi +
Cirsium tracyi +
species +
cylindric +
expanded +
0.55 cm5.5 mm <br />0.0055 m <br /> (1.05 cm10.5 mm <br />0.0105 m <br />) +
bristly-dentate to coarsely +
slender +
0.9 cm9 mm <br />0.009 m <br /> (1.4 cm14 mm <br />0.014 m <br />) +
50 cm500 mm <br />0.5 m <br /> (200 cm2,000 mm <br />2 m <br />) +
tree +, vine +, shrub +  and subshrub +