76. Galinsoga Ruiz & Pav. (quickweed)

(Canne, 1977)

Plants annual, with small taproots. Stems 8–70 cm long, erect or ascending, few- to many-branched, with fine longitudinal ridges and grooves, glabrous or sparsely to moderately pubescent with appressed or spreading hairs, the hairs sometimes gland-tipped toward the stem tip. Leaves opposite, long-petiolate to nearly sessile, the base slightly expanded and wrapping around the stem. Leaf blades lanceolate to broadly ovate, unlobed, mostly angled to short-tapered at the base, angled or tapered to a sharply pointed tip, the margins entire or more commonly sparsely to moderately toothed and with short, slender, more or less spreading hairs, the surfaces sparsely to densely pubescent with short, slender, more or less spreading hairs, usually with 3 main veins. Inflorescences of irregular, open, terminal panicles or sometimes merely loose clusters, these sometimes also from the upper leaf axils, rarely reduced to solitary heads, with small, leaflike bracts at the branch points, the heads appearing mostly long-stalked. Heads radiate. Involucre 2.5–5.0 mm long, 2.5–6.0 mm in diameter, cup-shaped to somewhat bell-shaped, the bracts in 2 somewhat unequal series. Involucral bracts 5–9, the outer series of 1–3 bracts somewhat shorter and narrower than the 4–6 inner bracts, green but relatively thin, noticeably several-nerved, ascending at the tip, oblong-elliptic to broadly ovate, glabrous or sparsely hairy. Receptacle convex or short-conical, not or only slightly elongating as the fruits mature, the florets subtended by chaffy bracts, these narrowly lanceolate to oblong-obovate, concave and more or less wrapping around the florets. Ray florets (3–)5(–8) in 1 series, pistillate (with a 2-branched style exserted from the short tube at flowering), the corolla 1.5–3.0 mm long, relatively broad, white (sometimes light pink elsewhere), the tubular portion with minute, dense glandular hairs, not persistent at fruiting. Disc florets 5–50, perfect, the corolla 0.8–1.5 mm long, yellow, the tube not expanded at the base or persistent at fruiting, glabrous, the 5 minute lobes glabrous. Style branches with the sterile tip short-tapered to a sharply pointed tip. Pappus of 12–20 slender, fringed scales, sometimes highly reduced or absent in the ray florets. Fruits 1.5–2.5 mm long, narrowly wedge-shaped to wedge-shaped in outline, 4-angled, those of the ray florets usually slightly flattened, the surface usually with minute, yellowish, ascending hairs, black, those of the disc florets shed individually with their subtending chaffy bract, those of the ray florets either shed separately or as an intact unit with the basally fused adjacent 2 or 3 chaffy bracts and the adjacent inner involucral bract. About 15 species, nearly worldwide.