2. Anagallis minima (L.) E.H.L. Krause (chaffweed)

Centunculus minimus L.

Pl. 508 a, b; Map 2318

Stems 5–14 cm long, spreading with ascending tips, rooting at the nodes, often forming mats, more or less circular in cross-section, not winged, glabrous. Leaves mostly alternate. Leaf blades 4–10 mm long, 2–4 mm wide, oblong to obovate. Flowers sessile or the stalks 0.5–1.0 mm long. Calyces deeply 4(5)-lobed, the lobes 2–3 mm long. Corollas deeply 4(5)-lobed, 1–2 mm long, more or less saucer-shaped, the lobes broadly lanceolate, light pink, becoming erect after flowering, the corolla withering but persistent as a cap at fruiting. Stamens 4(5), the filaments fused to the corolla for about half their length, glabrous, the anthers yellow. Ovary globose, with numerous seeds, the style 0.4–0.6 mm long. Fruits 1.5–2.5 mm long, more or less globose, yellowish brown to straw-colored. Seeds numerous, angular, the surface pitted, dark brown. 2n=22. May–August.

Scattered, mostly south of the Missouri River (nearly worldwide). Glades, openings of dry upland forests, savannas, rocky portions of upland prairies, banks of streams and rivers, bottomland prairies, margins of ponds, and fens; also fallow fields, old fields, roadsides, and open disturbed areas.

This species is often treated in the segreagate genus Centunculus L., which is separated from Anagallis by the alternate leaves and stamens fused to the minute corollas. Molecular studies have not entirely resolved resolved which placement is more appropriate (Martins et al., 2003; Manns and Anderberg, 2005).