Stems mat-forming, 3-14 dm. Leaves 1-10 × 5-5 cm; petiole 1-3 cm, winged; blade pale green abaxially, dark green adaxially, midvein and lateral veins raised abaxially, ovate-rhombic to triangular, base truncate, papillate with larger papillae abaxially. Inflorescences: peduncle to 2 mm. Flowers sometimes unisexual; calyx lobes spreading, yellow, ovate to half orbiculate, 2 mm; stamens clustered or scattered. Fruits turbinate, 8-12 mm; horns 4-6. Seeds smooth. 2n = 32. Flowering spring-fall. Sand dunes, bluffs, margins of coastal wetlands, disturbed areas; 0-500 m; introduced; Calif., Conn., Fla., Mass., N.C., Oreg., Pa., W.Va., Wis.; Mexico; South America; e Asia; Pacific Islands (New Zealand); Australia. Tetragonia tetragonioides is cultivated as a vegetable.