Spergularia atrosperma

Plants annual, delicate, 6-15 cm, glabrous or stipitate-glandular distally. Taproots filiform. Stems erect to ascending or arcuate-spreading, simple or branched proximally; main stem 0.3-1 mm diam. proximally. Leaves: stipules inconspicuous, dull white to tan, broadly triangular, 1-2.5 mm, apex acute to short-acuminate; blade filiform to linear, 0.5-3.5 cm, fleshy, apex blunt to apiculate; axillary leaf clusters absent. Cymes simple to 2-compound. Pedicels divergently spreading to reflexed in fruit. Flowers: sepals connate 0.2-0.5 mm proximally, lobes ± weakly 1-veined, elliptic to ovate, 1.8-2.7 mm, to 3.5 mm in fruit, margins 0.1-0.5 mm wide, apex broadly acute to rounded; petals white to rosy, ± ovate, 0.7-0.8 times as long as sepals; stamens 4-8; styles 0.4-0.8 mm. Capsules greenish, 3.3-5 mm, 1-1.3 times as long as sepals. Seeds black, often iridescent, submarginal groove usually absent, broadly ovate, compressed, 0.6-0.8 mm, shiny, sculpturing of parallel, wavy lines, not papillate (40×); wing absent or, rarely, incomplete, brownish, 0.1-0.2 mm, margins irregular.

Flowering summer. Alkaline places, mud flats, stream beds, sandy places; 30-1500 m; Calif., Nev.