9. Spergularia echinosperma Celakovský, Arch. Naturwiss. Landesdurchf. Böhmen. 4: 867. 1881.
Plants annual, delicate, 5-15 cm, stipitate-glandular throughout. Taproots slender. Stems erect to ascending, simple to diffusely branched proximally and distally; main stem occasionally prostrate, 0.2-1.5 mm diam. proximally. Leaves: stipules inconspicuous, silvery to dull tan, broadly triangular, 1.4-2.4 mm, shorter than wide, apex acuminate; blade linear, 0.5-3.5 cm, somewhat fleshy, apex blunt to apiculate; axillary leaf cluster usually absent. Cymes commonly 4-8+-compound. Pedicels reflexed and oriented to 1 side in fruit. Flowers: sepals connate 0.2-0.3 mm proximally, lobes 1-3-veined, lanceolate to ovate, 2.5-3.6 mm, to 4 mm in fruit, margins 0.1-0.5 mm wide, apex rounded; petals white to pink or rosy, lanceolate, 0.4-0.6 times as long as sepals; stamens 1-4(-5); styles 0.3-0.4 mm. Capsules greenish to tan, 2.8-4 mm, 0.9-1.4 times as long as sepals. Seeds reddish brown to blackish, silver tinged, with submarginal groove, pyriform, ± compressed, 0.5-0.7(-0.8) mm, shiny, slightly roughened, with dense, gland-tipped papillae and appearing echinate (30×); wing usually absent, whitish to reddish brown, 0.1-0.2 mm wide, margins irregular and not papillate. 2n = 18, 36 (both Europe).
Flowering spring. Dunes, clay flats, sandy river banks; 0-20+ m; introduced; Ala., Ga., La., Tex.; Europe.