75. SENÈCIO, Tourn. Groundsel.
Heads many-flowered; rays pistillate, or none; involucre cylindrical to bell-shaped, simple or with a few bractlets at the base, the scales erect-connivent. Receptacle flat, naked. Pappus of numerous very soft and slender capillary bristles.—Herbs, in the United States, with alternate leaves and solitary or corymbed heads. Flowers chiefly yellow. (Name from senex, an old man, alluding to the hoariness of many species, or to the white hairs of the pappus.)
[*] Root annual or in n. 3 biennial; heads several or many in a corymb; herbage glabrous or soon becoming so.
[+] Rays none or minute.
S. vulgàris, L. (Common Groundsel.) Low, corymbosely branched, glabrate; leaves pinnatifid and toothed; clasping tips of involucral scales blackish; rays none.—Waste grounds. July–Sept. (Adv. from Eu.)
S. viscòsus, L. Coarser, viscid-pubescent and strong-scented; leaves 2-pinnatifid; scales not black-tipped; rays minute.—Waste grounds, coast of N. Eng. (Nat. from Eu.)
[+][+] Heads conspicuously radiate.
1. S. lobàtus, Pers. (Butter-weed.) Rather tall; leaves somewhat fleshy, lyrate or pinnate, the divisions or leaflets crenate or cut-lobed, variable; heads small in a naked corymb; rays 6–12, conspicuous.—Wet grounds, N. Car. to S. Ill., Mo., and southward. April–July.
2. S. palústris, Hook. Annual or biennial, loosely woolly or glabrate; stem stout, 6´–2° high; leaves oblong-lanceolate, irregularly toothed or laciniate, the upper with a heart-shaped clasping base; rays 20 or more, short, pale yellow; pappus copious and becoming very long.—Wet ground, Iowa to N. Wisc., Minn., and northward. June. (Eu.)
[*][*] Root perennial; heads small or middle-sized, in a naked corymb.