1. Androsace occidentalis Pursh (western rock jasmine)

A. simplex Rydb.

Pl. 508 g, h; Map 2319

Plants annual. Aerial stems absent. Scapes 1 to more commonly several per plant, 3–12 cm long, erect or arched upward, finely pubescent with minute, branched hairs. Leaves all basal, sessile. Leaf blades 5–20 mm long, 2–4 mm wide, lanceolate to ovate, the margins inconspicuously toothed, the upper surface mintuely hairy, the undersurface glabrous. Inflorescences simple umbels with 2–10 flowers, with an involucre of bracts, these 3–4 mm long, 1.5–2.0 mm wide, the flower stalks 10–30 mm long, unequal, ascending, finely hairy. Calyces 3–6 mm long, the tube 5-ridged, glabrous or nearly so, the lobes shorter than the tube, lanceolate, ascending, minutely hairy. Corollas shorter than to about as long as the calyces, 2–4 mm long, white, the (4)5 lobes loosely ascending to spreading, withering but tending to persist at fruiting. Stamens 5, the short filaments attached near the middle of the corolla tube, the tiny anthers oval. Ovary 1 mm in diameter, hemispherical, the style about 0.2 mm long, the stigma minute, capitate. Fruits capsules, 1–2 mm long, globose, membranous toward the base, hardened toward the tip, dehiscing incompletely from the tip by 5 valves. Seeds 0.8–1.2 mm long, 0.8 mm wide, triangular in outline, the surface with a network of ridges and pits, dark brown. 2n=20. March–June.

Scattered in the state, but uncommon or apparently absent from the Mississippi Lowlands Division, as well as the eastern portion of the Ozarks and eastern portion of the Glaciated Plains (Idaho to Ohio south to California, Texas, and Arkansas; Canada; introduced in Massachusetts). Glades, ledges and tops of bluffs, and openings of mesic to dry upland forests; also old fields, crop fields, pastures, lawns, cemeteries, railroads, roadsides, and open, disturbed areas.

This inconspicuous species is easily overlooked in the field.