Curly-cup gumweed

Grindelia squarrosa, curly-cup gumweed, is a biennial to short-lived perennial herb of the Asteraceae family, native to the central and western United States and adjacent Canada. It grows 20-100 cm tall, with erect, branched, glabrous, often reddish stems arising from a stout taproot. The alternate, sessile leaves are oblong to oblanceolate, 2-7 cm long, with conspicuously toothed or serrate margins and resin-dotted surfaces. The species is most readily identified by its yellow, daisy-like flower heads 2-4 cm across, in which the involucral bracts are strongly recurved and exude a sticky, milky-white resinous gum, especially before bloom. Disc and ray florets are both bright yellow. The plant flowers from midsummer to autumn and produces small ribbed achenes with a deciduous pappus of two or three short awns. It thrives in dry prairies, roadsides, overgrazed pastures, and disturbed soils, often forming dense colonies in saline or alkaline ground.