2. Packera glabella (Poir.) C. Jeffrey (butterweed)

Senecio glabellus Poir.

Pl. 299 c, d; Map 1252

Plants annual or less commonly biennial, lacking rhizomes or stolons. Stems mostly 1, rarely 2, 15–80 cm long, sometimes appearing somewhat inflated, glabrous or inconspicuously hairy. Basal leaves usually absent at flowering, short- to less commonly long-petiolate, the petioles rarely cobwebby when young, glabrous at flowering, the blades 3–20 cm long, pinnately compound with several (rarely few) pairs of lateral pinnae, less commonly only pinnately lobed, oblanceolate to elliptic-obovate in outline, the lobes or leaflets rounded at the tip, sometimes deeply few-lobed, the margins otherwise scalloped or with blunt to sharp teeth, the surfaces glabrous. Stem leaves gradually reduced toward the stem tip, sessile or nearly so, the blades mostly deeply pinnately lobed, the lower leaves sometimes with the blades pinnately compound, the lobes or leaflets sometimes deeply lobed, the terminal lobe or leaflet broadly wedge-shaped to nearly circular, shorter than to about as wide as long, the margins otherwise scalloped or bluntly to sharply toothed, the surfaces glabrous. Involucre 4–7 mm long, glabrous. Ray florets usually 7–13, the lobe 5–12 mm long. Fruits 2.5–3.0 mm long, glabrous or more commonly hairy, especially along the ribs. 2n=46. April–June.

Scattered, principally in the Big Rivers and Mississippi Lowlands Divisions, but also sporadically elsewhere in the eastern half of the state (southern U.S. west to South Dakota and Texas; extirpated from Canada). Bottomland forests, swamps, banks of streams, rivers, and sloughs, bottomland prairies, and less commonly moist depressions of upland prairies and sand prairies, also crop fields, fallow fields, railroads, roadsides, and moist, open, disturbed areas.