Pleiacanthus

(Nuttall) Rydberg

Fl. Rocky Mts., 1069. 1917.

Common names: Thorny skeletonweed
Etymology: Greek pleio, in compounds, more than usual, and acanthos, a prickly plant, or acantha, thorn
Basionym: Lygodesmia D. Don subgen. Pleiacanthus Nuttall Trans. Amer. Philos. Soc., n. s. 7: 444. 1841
Treatment appears in FNA Volume 19. Treatment on page 361. Mentioned on page 219, 360.
 TaxonIllustrator 
FNA19 P37 Prenanthella exigua.jpegPrenanthella exigua
Pleiacanthus spinosus
Glyptopleura setulosa
Yevonn Wilson-Ramsey
Sheila Flinchpaugh
John Myers

Perennials, 10–50 cm; root crowns woody, branched. Stems 1–4 [–8], branches divaricate, rigid, spine-tipped, with conspicuous tufts of light-brown, wool in axils of bud-scales at and just below-ground level, otherwise glabrous (bud-scales lanceolate, 8–30 × 5–8 mm, entire). Leaves cauline; sessile; proximal blades linear, margins entire; distal bractlike. Heads (± subsessile, erect), borne singly or in paniculiform arrays. Peduncles not inflated, not bracteate. Calyculi of 4–6 bractlets (unequal, lengths to 1/2 phyllaries). Involucres cylindric, 2–3+ mm diam. Phyllaries 3–5 in ±1 series, linear-lanceolate. Receptacles flat or convex, smooth, glabrous, epaleate. Florets 3–5; corollas pink or lavender. Cypselae tan, columnar, apices truncate (beaks 0), with 5 equal faces, separated by weakly rounded ribs, each face with central, narrow, shallow, longitudinal groove, glabrous; pappi persistent, of 50–60, distinct, light tan, barbellate bristles (of 2 lengths). x = 8.

Distribution

w United States

Discussion

Species 1.

Selected References

None.

"fine" is not a number.

... more about "Pleiacanthus"
rounded;acute +
scarious +
ovate +  and lanceolate +
paniculiform +
indeterminate +  and determinate +
L. D. Gottlieb +
(Nuttall) Rydberg +
decurrent +
Lygodesmia +
compound +  and simple +
tuberculate +, rugose +, muricate +  and smooth +
filiform +
Thorny skeletonweed +
zygomorphic +, actinomorphic +  and (3-)5-merous +
lavender +  and pink +
w United States +
Greek pleio, in compounds, more than usual, and acanthos, a prickly plant, or acantha, thorn +
winged +  and beaked +
dispersed +
in paniculiform arrays +  and singly +
indeterminate +
each +  and sessile +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
below-ground +
divided +, lobed +  and dentate +
2-carpellate +
persistent +
not inflated +
connate +  and distinct +
1 +, 3 +  and 5 +
subequal +  and unequal +
Fl. Rocky Mts., +
convex;flat +
rounded +
exalbuminous +
4 (?) +  and 8 (?) +
prostrate +  and ascending +
1 +  and 4 +
appendaged +  and truncate +
papillate +
Undefined tribe Lactuceae +
Pleiacanthus +
Asteraceae tribe Cichorieae +
conspicuous +
10 cm100 mm <br />0.1 m <br /> (50 cm500 mm <br />0.5 m <br />) +
shrub +  and subshrub +