25. Minuartia pusilla (S. Watson) Mattfeld, Bot. Jahrb. Syst. 57(Beibl. 126): 28. 1921.
Annual sandwort, dwarf stitchwort
Arenaria pusilla S. Watson, Proc. Amer. Acad. Arts 17: 367. 1882; Alsinopsis pusilla (S. Watson) Rydberg
Plants annual. Taproots threadlike. Stems spreading to erect, green, 1-5 cm, glabrous, inter-nodes of all stems 2-10 times as long as leaves. Leaves not overlapping, irregularly spaced, connate proximally, with loose, mostly herbaceous sheath 0.2-0.3 mm; blade ascending to widely spreading, green, concave proximally, flat distally, obscurely 1-veined, awl-shaped to lanceolate, 1.5-5 × 0.2-1.5 mm, flexuous, margins not thickened, scarious throughout or proximally, smooth, apex green or purple, acute to obtuse, flat to navicular, often shiny, glabrous; axillary leaves absent. Inflorescences 2-9-flowered, open cymes; bracts subulate, herbaceous, margins scarious proximally. Pedicels 0.1-0.5 cm, glabrous. Flowers: hypanthium disc-shaped; sepals 1-veined, or weakly 3-veined in proximal 1/ 5, ovate to lanceolate (herbaceous portion lanceolate to narrowly so), 1.5-3.5 mm, not enlarging in fruit, apex green or purple, acute to acuminate, not hooded, glabrous; petals narrowly lanceolate, 0.5-1 times as long as sepals, apex narrowly acute, entire, or absent. Capsules on stipe ca. 0.1 mm, ± ovoid, ca. 3 mm, equaling or longer than sepals. Seeds brown or reddish, asymmetically reniform with radicle prolonged into beak, not compressed, 0.5-0.6 mm, minutely papillate.
Flowering spring-summer. Plains, pine barrens, dry rock cliffs; 50-2400 m; B.C.; Calif., Idaho, Nev., Oreg., Utah, Wash.