A. Gray

Mem. Amer. Acad. Arts., n. s. 4: 65. 1849.

Etymology: Greek trichos, hair, and koronos, crown, apparently alluding to setiform pappus elements
Treatment appears in FNA Volume 21. Treatment on page 487. Mentioned on page 460, 488.

Annuals or perennials, 10–30 cm (aquatic or subaquatic). Stems decumbent to erect, branched from bases or ± throughout (sometimes rooting at proximal nodes). Leaves cauline; mostly opposite (distal sometimes alternate); sessile; blades usually 1–3-nerved from near bases, oblong to elliptic or lanceolate, margins usually ± dentate (at least distally), faces glabrous or sparsely pilose to pilosulous and glabrescent, sometimes minutely gland-dotted. Heads discoid, borne singly or in loose or open, corymbiform arrays. Involucres mostly hemispheric or broader, 3–4(–5) mm diam. Phyllaries persistent, 18–30 in 2–3 series, obscurely 3–4-nerved, lanceolate, ± equal (herbaceous). Receptacles convex to conic, epaleate (warty). Florets 75–125; corollas whitish or pinkish to purplish, throats tubular-funnelform (lengths ca. 2 times diams.); styles: bases not enlarged, glabrous, branches linear-filiform (distally densely papillose). Cypselae weakly fusiform, 4–5-ribbed, scabrellous on ribs; pappi persistent, of 2–6+ laciniate or fimbriate to setiform scales or coarsely barbellate bristles. x = 15.


Tex., Mexico, introduced in Calif.


Species 2 (1 in the flora).