Cluster or pea rose

Rosa rivalis Eastwood

Plants often forming thickets. Stems loosely to densely clustered, 10–25 dm; infrastipular prickles primarily (1–)2, 2–10 mm. Leaves 5–10 cm; leaflets 5–7(–9), most commonly 7, terminal blade 15–35 mm. Inflorescences (1–)3–12-flowered. Flowers: sepal tip to 10 mm, abaxial surfaces usually stipitate-glandular; carpels 22–35. Hips usually globose, rarely subglobose, 7–10 mm diam., abruptly narrowed to neck 1.5–3 mm diam. Achenes 25–35. 2n = 14.

Flowering Jun–Aug. Coasts, stream banks, riparian areas, open and low places, sedge meadows, swamps, roadside hedges, thickets, montane oak belts; 30–2100 m; B.C.; Calif., Oreg., Wash.

Subspecies pisocarpa encompasses traditional circumscriptions of Rosa pisocarpa. It occurs in coastal regions from southwestern British Columbia to northern California, west of and within the Cascade Mountains. Stems tend to have paired erect prickles, stipitate-glandular sepals with elongate tips, and clusters of pea-shaped hips. Limited populations intermediate with R. woodsii subsp. ultramontana occur in Cascade Mountain passes along the Fraser River (British Columbia), the Columbia River (Oregon and Washington), and the Klamath River (southern Oregon). Reports of R. pisocarpa from farther east (for example, R. J. Davis 1952) were based on R. woodsii or other species.

The Snohomish and Squaxin of Puget Sound, Washington, used subsp. pisocarpa root decoctions to treat sore throats, and bark infusions for after child-birth, respectively (D. E. Moerman 1998). Southeastern Vancouver Island Saanich have used young shoots for food in the spring; ripe hips were eaten raw in the fall. They also boiled branches to make a decoction, which was used to flush the eyes of those not able to see well; this preparation served to treat any eye problem, including cataracts (N. J. Turner, pers. comm.).