5. Frangula obovata (Kearney & Peebles) G. L. Nesom & J. O. Sawyer, Phytologia. 91: 302. 2009.
Pearleaf buckthorn Pearleaf buckthorn
Rhamnus betulifolia Greene var. obovata Kearney & Peebles, J. Wash. Acad. Sci. 29: 486. 1939 (as betulaefolia); Frangula betulifolia (Greene) Grubov subsp. obovata (Kearney & Peebles) Kartesz & Gandhi
Shrubs, 1–2.5 m. Stems red to brown or gray-brown, glabrous or pubescent. Leaves deciduous; petiole 5–14 mm; blade usually equally green on both surfaces, not glaucous, obovate to oblong-obovate or oblong, (4–)5–9 x 3.2–6 cm, 1.2–1.8(–2.5) times longer than wide, subcoriaceous to distinctly coriaceous, base truncate to subcordate, margins serrulate to nearly entire, apex obtuse to truncate or rounded, both surfaces minutely puberulous to hirtellous, glabrescent; secondary veins (5–)6–8(–9) pairs. Inflorescences umbels, pedunculate, 2–12-flowered. Pedicels 3–10 mm. Stigmas 3-lobed. Drupes black, globose, 5–8 mm; stones 3.
Flowering Apr–Jun. Hanging gardens, cliff faces, talus, canyon bottoms, seepage below cliffs, stream and creek banks; 1300–2400 m; Ariz., Colo., Nev., Utah.
Frangula obovata is known from Clark County, Nevada, across northern Arizona and southern Utah to southwestern Colorado; its distribution does not overlap that of F. betulifolia.