Galinsoga quadriradiata is an annual herb that germinates May-June, 20-70 cm tall, slender, hairy, young stems often reddish-hairy, freely branched; branches opposite.
Leaves opposite, stalk to 6 cm, lower leaves long-stalked, upper leaves almost stalkless, blade egg-shaped, 2.5-7 cm long, 1.5-5 cm wide, hairy on both sides, tip pointed to blunt, base blunt to wedge-shaped, margin toothed.
Flowers white rays 5, 0.2-0.3 cm long, strongly 3-toothed, disk flowers yellow, 15-65; self-fertile, heads to 0.8 cm long, 1 cm wide, outer bracts 1-2 leaf-like, deciduous, basal scales about as long as flower tube, margin fringed; blooms about 24 days after germination; blooms and fruits June-Nov.
Fruit dry, 1-seeded achene, blackish, about 0.1 cm long.
Wetland status: UPL.
Frequency in NYC: Occasional.
Origin: Central & South America (USDA Forest Service 2006).
Habitat: Disturbed, open areas, vacant lots, an agricultural weed. Prefers damp, rich soil.
Notes: Able to root from cut stems. Very sensitive to freezing. A host for several nematodes that attack agricultural crops. Hosts for numerous insects including Chrysomelid beetles, aphids, thrips, and Lepidopterans; also attacked by various nematodes and viruses (Warwick and Sweet 1983).