Show Lower Taxa
Gen. Pl., 168. 1789
Etymology: Greek rhagado, crack or split, and - olus, diminutive, perhaps alluding to gaps between margins of enfolding phyllaries
Treatment appears in FNA Volume 19. Treatment on page 300. Mentioned on page 214, 218.
Annuals, 5–60+ cm; taprooted. Stems usually 1, erect, branched distally, glabrous. Leaves basal and cauline (mostly cauline at flowering); basal sessile or ± petiolate, distal ± sessile; blades ovate-lanceolate to lanceolate or linear (often runcinate), margins entire or dentate to pinnately lobed (faces glabrous or ± hispid). Heads in ± corymbiform arrays (terminal heads often surpassed by others). Peduncles not inflated, rarely bracteolate. Calyculi of 5, ovate to deltate bractlets. Involucres campanulate to cylindric, 2–4+ mm diam. (larger in fruit). Phyllaries (3–)5–8 in 1 series (closely enfolding ovaries/cypselae of subtended florets; ± patent in fruit), linear, equal, margins often scarious, apices acuminate (abaxially glabrous or ± hispid to scabrous). Receptacles ± flat, smooth or ± pitted, glabrous, epaleate. Florets 5–6(–10+); corollas yellow. Cypselae brownish, heteromorphic; outer (tardily falling with enfolding phyllary) ± terete, narrowed distally, straight to arcuate, not beaked, ribs 0, faces glabrous; inner (readily falling) terete, straight to ± coiled, faces glabrous or closely hirtellous; pappi 0. x = 5.
Species 1 or 2 (1 in the flora).