34. Crepis L. (hawksbeard)
Contributed by
David J. Bogler and George Yatskievych
Plants annual, biennial,
or perennial herbs, taprooted (with rhizomes or woody rootstocks elsewhere).
Latex white. Stems erect to loosely ascending, unbranched or branched, finely
ridged, variously hairy or glandular. Leaves basal and alternate, glabrous or
variously hairy and sometimes also glandular, sessile or short- to
long-petiolate. Basal leaves with the blades (at least the largest) pinnately
lobed, variously shaped, the margins otherwise entire or toothed, with 1 main
vein visible and sometimes also a faint network of anastomosing secondary
veins. Stem leaves similar to the basal ones, but often sessile, smaller,
narrower, and generally less divided, the base with a pair of narrowly
triangular clasping lobes. Inflorescences mostly terminal panicles, sometimes
appearing as solitary heads or loose clusters at the stem or branch tips.
Involucre not or only slightly elongating as the fruits mature, cup-shaped or
somewhat bell-shaped, the bracts in 1(2) longer, inner series and 1 shorter,
outer series, the inner bracts similar in size, mostly lanceolate, the margins
sometimes thin and pale, the tip ascending at flowering; the outer bracts
unequal in size, linear to broadly ovate, loosely ascending to spreading.
Receptacle naked or sometimes with minute hairs around the base of each floret.
Ligulate florets 10–70 per head. Corollas lemon yellow to orangish yellow,
sometimes purplish-tinged on the undersurface. Pappus of numerous bristles,
these white (slightly off-white in C. pulchra), often shed irregularly
at fruiting. Fruits nearly cylindrical to narrowly oblong-elliptic in outline,
beaked or not beaked, not flattened, circular or somewhat 5–10-angled in
cross-section, with 10–20 longitudinal ribs, these often minutely roughened or
barbed, glabrous, reddish brown to dark brown, the pappus attached to a
sometimes expanded tip. About 200 species, North America, South America,
Europe, Asia, Africa.
Crepis was the subject of a monumental
monographic study by Ernest Babcock (1947a, b) that is still studied by
students of plant taxonomy as a landmark publication in biosystematics.