Herbs, perennial, laxly cespitose, mat-forming, glabrous. Stems ascending, branched, (stolonif-erous), not bearing rosettes. Leaves alternate, (densely imbricate on nonflowering shoots), usually in 6 rows (fewer on flowering shoots), ascending, sessile; blade bright green, not glaucous, linear, subterete to terete, 3-6 × 0.8-2 mm, base spurred, not scarious, apex obtuse. Flowering shoots erect, simple or branched, 6-15 cm; leaf blades linear, base spurred; offsets not formed. Inflorescences moderately lax cymes, 5-25-flowered, (1-)2-3(-4)-branched; branches spreading, sometimes forked; bracts similar to leaves, smaller. Pedicels to 0.5 mm. Flowers 5(-6)-merous; sepals erect, distinct, yellowish green, linear-elliptic, unequal, 0.8-1 × 0.4-0.5 mm, apex obtuse; petals spreading, distinct, bright yellow, lanceolate, not carinate, 3-4 mm, apex acute or acuminate; filaments yellow; anthers yellow; nectar scales yellow, square. Carpels divergent in fruit, distinct, dark brown. 2n = 74, 111, 148, 185.

Flowering late spring-summer. Roadsides, waste places; 0-500 m; introduced; Ont.; Conn., Ill., Ind., Mass., Mich., N.H., Ohio, Vt.; Europe.

Sedum sexangulare was first reported as naturalized in the United States in 1942. The mature carpels have narrow brown lips along the adaxial suture.