PLANT: Shrubs or small trees, unarmed. STEMS: several to many, erect to ascending, smooth; branches mostly alternate; twigs canescent; bud scales absent. LEAVES: evergreen or deciduous, alternate, petiolate; blades elliptic to oblong or obovate, pinnately-veined, serrate to entire, pubescent to tomentose. INFLORESCENCE: axillary cymes of 2-35 flowers. FLOWERS: perfect, pedicellate; hypanthium hemispheric, 2 mm in diameter, loosely villous; sepals 5, yellow, triangular; petals 5, ca. 1 mm long; stamens 5; stigma 2-3-lobed. FRUITS: drupes, purplish-black when ripe, spherical, glabrous; stones 2-3, smooth. NOTES: 8 spp. in N. Amer. (2 in AZ). (Fragile; medieval name refers to the brittle twigs of alder buckthorn.) Frangula was formerly treated as a subgenus or section of the genus Rhamnus. REFERENCES: Christie, Kyle, Michael Currie, Laura Smith Davis, Mar-Elise Hill, Suzanne Neal, and Tina Ayers. 2006. Vascular Plants of Arizona: Rhamnaceae. CANOTIA 2(1): 23-46.