Acroptilon

Cassini in F. Cuvier

in F. Cuvier, Dict. Sci. Nat. ed. 2, 50: 464. 1827.

Common names: Russian knapweed creeping knapweed Russian centaurea mountain-bluet Turkestan thistle centaurée de Russie
Etymology: Greek akron, tip, and ptilon, feather, describing the pappus bristles
Treatment appears in FNA Volume 19. Treatment on page 171. Mentioned on page 7, 58, 67, 83.

Perennials, 30–100 cm, not spiny. Stems erect, branched distally or throughout, branches ascending, not winged. Leaves: basal and proximal cauline; sessile or petiolate; blade margins coarsely dentate or 1–2-pinnately lobed, margins of mid and distal cauline dentate or entire, faces loosely tomentose or glabrate, puberulent and resin-gland-dotted. Heads discoid, in (leafy-bracted) corymbiform or paniculiform arrays. Involucres ovoid to subspheric, constricted, 6–10 mm diam. Phyllaries many in 6–8 series, outer round to ovate, bases tightly appressed, margins entire, apices widely scarious, obtuse or acute, inner lanceolate, margins entire, apices acute to acuminate, those of innermost bristly-ciliate or plumose. Receptacles flat, epaleate, bearing setiform scales (“flattened bristles”). Florets 15–36; corollas blue, pink, or white, tubes very slender, usually bent distally, throats abruptly expanded, lobes linear; anther bases short-tailed, apical appendages oblong; style-branches: fused portions with slightly swollen basal nodes minutely hairy, distally papillate, distinct portions very short, apices triangular. Cypselae obovoid, slightly compressed, smooth or with indistinct ribs, glabrous, attachment scars subbasal; pappi ± falling, of many unequal setiform scales (“flattened bristles”), proximally barbed, distally plumose (at least the longer). x = 13.

Distribution

Introduced; Eurasia

Discussion

Species 1.

In most American floristic literature Acroptilon has been included within Centaurea, from which it differs by the subbasal rather than lateral attachment scars on the cypselae and the absence of sterile outer florets. The chromosome base number x = 13 is higher than that in most species of Centaurea in the strict sense. Molecular phylogenetic studies of the relationships of Cynareae genera (A. Susanna et al. 1995) support the segregation of Acroptilon from Centaurea.

Lower Taxa

"fine" is not a number.

... more about "Acroptilon"
short-tailed +
scarious +
paniculiform +  and corymbiform +
indeterminate +  and determinate +
David J. Keil +
Cassini in F. Cuvier +
decurrent +
Asteraceae tribe Cynareae +
compound +  and simple +
lobed +  and dentate +
10-nerved or 20-nerved +  and rugose +
Russian knapweed +, creeping knapweed +, Russian centaurea +, mountain-bluet +, Turkestan thistle +  and centaurée de Russie +
actinomorphic +
white +, pink +  and blue +
with indistinct ribs +  and smooth +
compressed +  and obovoid +
fertile +  and bisexual +
Greek akron, tip, and ptilon, feather, describing the pappus bristles +
resin-gland-dotted +, puberulent +, glabrate +  and tomentose +
pistillate +, staminate +  and neuter +
winged +  and beaked +
dispersed +
in corymbiform , paniculiform or racemiform , arrays +  and singly +
indeterminate +
each +  and sessile +
0.6 cm6 mm <br />0.006 m <br /> (1 cm10 mm <br />0.01 m <br />) +
ovoid;subspheric +
constricted +
petiolate +  and sessile +
cauline +  and basal +
deltate +, usually narrowly triangular +  and more or less linear +
usually lobed +  and dissected +
round +  and ovate +
2-carpellate +
persistent +
papillate +  and smooth +
distinct +  and fused +
papillate +
in F. Cuvier, Dict. Sci. Nat. ed. +
bearing subulate enations +, hairy +  and bristly +
flat;convex +
watson1980a +
indistinct +
setiform +
unequal +
exalbuminous +
appendaged +  and truncate +
dilated +  and swollen +
enlarged +
Compositae +
Acroptilon +
Asteraceae tribe Cardueae +
expanded +
slender +
entire +, dentate +  and not spiny +
30 cm300 mm <br />0.3 m <br /> (100 cm1,000 mm <br />1 m <br />) +
tree +, vine +, shrub +  and subshrub +