Annuals [biennials], 15-150 cm; fibrous-rooted. Stems 1, erect, simple or branched, glabrate to sparsely or densely pilose, hairs often stipitate-glandular. Leaves basal and cauline (not in rosettes); narrowly winged-petiolate; blades ovate to suborbiculate (thin), margins entire, dentate, or lyrate-pinnatifid proximally (terminal lobes larger than laterals, faces glabrate to sparsely hirsute; distal sessile, lanceolate, reduced). Heads in open, corymbiform to thyrsiform arrays. Peduncles (slender) slightly inflated distally, ebracteate. Calyculi of 4-5 subulate or scalelike, glabrous bractlets. Involucres cylindric to campanulate, 2-5 mm diam. Phyllaries 8-10 in 1 series, linear-oblong, subequal, (strongly keeled) margins green, not scarious, apices acute, faces glabrous. Receptacles flat, smooth, glabrous, epaleate. Florets 8-15; corollas yellow. Cypselae dimorphic (outer much longer than inner), tan to golden brown, subcylindric, curved, terete to slightly compressed, not beaked, ± 20-ribbed, glabrous; pappi 0. . = 7.
Lapsana formerly included about 9 species, some from eastern Asia. Based on cladistic analysis of morphologic characters, the eastern Asian species have been removed to Lapasanastrum, a strongly supported monophyletic group characterized by spreading phyllaries and distinctive fruit anatomy (J. H. Pak and K. Bremer 1995).
Fls all ligulate and perfect, yellow; invol cylindric-campanulate, minutely calyculate, the inner bracts subequal, uniseriate, keeled; achenes narrow, subterete or slightly compressed, often curved, narrowed to both ends, usually more gradually so downwards, 18-30-nerved, 5 or 6 of the nerves generally stronger; pappus none; branching, annual, lactiferous herbs, with alternate, entire to pinnatifid lvs and several to many small, rather few-fld heads, the peduncles tending to be apically pale and indurate. 9, temp. Eurasia.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.