310. Thelesperma Lessing, Linnaea. 6: 511. 1831.
[Greek thele, nipple, and sperma, seed, alluding to papillate cypselae of original species]
John L. Strother
Annuals, perennials, or subshrubs, 10–70+ cm. Stems usually 1, erect, branched distally or ± throughout. Leaves mostly basal, basal and cauline, or mostly cauline; mostly opposite (distal rarely alternate); blades usually 1(–3)-pinnately lobed (ultimate lobes oblanceolate to filiform), faces usually glabrous, rarely hairy. Heads radiate or discoid, borne singly or in loose, corymbiform arrays. Calyculi of 3–8+ distinct, usually spreading or reflexed, usually linear to subulate, herbaceous bractlets. Involucres hemispheric to urceolate, 4–15+ mm diam. Phyllaries 5–8 in ± 2 series, persistent, connate 1/5–7/8+ their lengths, lance-ovate to ovate, ± equal, ± leathery to membranous, margins (of distinct apices) scarious. Receptacles flat to convex, paleate; paleae falling, (whitish with red-brown striae, each ± appressed to abaxial face of subtended cypsela), obovate to oblong, scarious. Ray florets 0 or ca. 8, neuter; corollas yellow or red-brown, or bicolored (yellow and red-brown). Disc florets 20–100+, bisexual, fertile; corollas yellow (with red-brown nerves) or red-brown, either with throats equal to or longer than 5, ± deltate, ± equal lobes, or with throats shorter than 5, ± lance-linear, ± unequal lobes (in either form, the abaxial sinus usually ± deeper than others). Cypselae (dark red-brown or stramineous) outer often arcuate, shorter, inner more columnar, usually some or all ± obcompressed (each usually shed together with its subtending palea), faces smooth or papillate to tuberculate or verrucate, margins sometimes ± winged; pappi 0, or persistent, of 2 retrorsely ciliate, subulate scales or awns. x = 12.
Species 10+ (9 in the flora): w North America, Mexico, South America.
Hansen, C. J., L. Allphin, and M. D. Windham. 2002. Biosystematic analysis of the Thelesperma subnudum complex (Asteraceae). Sida 20: 71–96. Greer, L. F. 1997. Thelesperma curvicarpum (Asteraceae), an achene form in populations of T. simplicifolium var. simplicifolium and T. filifolium var. filifolium. Southw. Naturalist 42: 242–244.