1. Penthorum Linnaeus, Sp. Pl. 1: 432. 1753; Gen. Pl. ed. 5, 197. 1754.
Ditch-stonecrop [Greek pente, five, and horos, limit or landmark, alluding to 5-merous flower] Ditch-stonecrop [Greek pente, five, and horos, limit or landmark, alluding to 5-merous flower]
Plants rhizomatous or stoloniferous. Stems decumbent or ascending to erect, glabrous proximally, stipitate-glandular distally. Leaf blades elliptic-lanceolate to oblanceolate, base acuminate, apex acuminate. Inflorescences pedunculate, branches stipitate-glandular. Pedicels present, stipitate-glandular. Flowers: hypanthium stipitate-glandular; sepals green or reddish, triangular to narrowly triangular; petals inconspicuous, white or greenish white; filaments white, yellow, or pink, glabrous; anthers yellow or pink. Seeds minutely tuberculate. x = 8 or 9.
Species 2 (1 in the flora): North America, Europe (Russia), Asia.
Penthorum chinense Pursh is known from European Russia and Asia.