Native California Roses

copyright Barbara Ertter, 2001
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Rosa pisocarpa A. Gray
"Cluster Rose"

Description Distribution Discussion Horticultural Notes Nomenclature Links

Lank shrub at edges of or in open forest understory. Prickles few, paired at nodes, straight, somewhat thick-based. Flowers usually several per inflorescence. Hips globose with elongate sepal-tips.

DESCRIPTION: Lank shrub to thicket, generally 5--25 dm tall. Stem generally black; prickles few, generally paired at nodes, sometimes nearly lacking, generally flattened, somewhat thick-based, straight, often whitely contrasting with stem. Leaf 5--10 cm; stipule margins generally glandular; leaflets 2--3 per side, sparsely hairy to glabrous; terminal leaflet 15--40 mm long, obovate-elliptic, the base acute to obtuse, the tip obtuse; leaf-margins single-toothed, generally glandless. Inflorescence generally 2--10-flowered; pedicels 10--20 mm long, generally glabrous, glandless. Flowers: body of hip in flower generally 3--6 mm wide, glabrous, neck of hip generally 2--3 mm wide; sepals generally glandular, sepal-tip generally longer than sepal-body, entire; petals 15--20 mm long; pistils generally > 10 in number. Hip globose, 10 mm wide, glabrous, neck 3--4 mm wide, sepals persistent. n = 7. Blooming June to August. Generally moist or shady areas at forest edge; 30--2100 m elev.

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Northern Coast Ranges and Klamath/Siskiyou Ranges in northern California, extending north on the west side of the Cascades to British Columbia.

Additional distributional representations available from links at entry for this species in the Jepson Interchange for On-Line Floristics

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DISCUSSION: Flowers of Rosa pisocarpa are generally several, giving rise to the common name of Cluster Rose. Hips are round and glabrous, and the sepals have prominent tips. The straight prickles are relatively sparse, characteristically occurring in pairs at the nodes, or even nearly absent. The frequent near-absence of prickles, especially in the upper parts of the plants that are often all that is collected for herbarium specimens, makes it all the more difficult to determine the actual distribution of R. pisocarpa in that part of northern California where the ranges of R. pisocarpa, R. californica, and R. woodsii var. ultramontana overlap, given that prickles are among the most critical characters for distinguishing the three species.

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HORTICULTURAL NOTES: Desirable horticultural features of the Cluster Rose include the clustered flowers and sparse prickles, which often contrast distinctively with the dark stems.

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R. pisocarpa A. Gray, Proc. Amer. Acad. Arts 8: 282. 1872: E. Hall s.n.-- Oregon (possible IS at NY!)

Possible Synonyms (working list):
R. copelandii Greene, Leafl. Bot. Observ. Crit. 2: 264. 1912: Copeland [Baker 3875]-- Mt Eddy, Siskiyou Co., CA (HT: NDG11152!; ISO: CAS! MO! NY! US!)
R. corymbiflora Rydb., N. Amer. Fl. 22: 519. 1918: Eastwood 1404-- between Pitt & Baird, Shasta Co., 25 Jul 1912 (HT: Arnold Arb.; IS: NY!)
R. eastwoodii Rydb., N. Amer. Fl. 22: 527. 1918: Eastwood 2100-- Sisson, Siskiyou Co, CA, 4 Sep 1912 (HT: Arnold Arb.; IS: CAS! NY!)
R. pringlei Rydb., Bull. Torrey Bot. Club 44: 79. 1917: Pringle s.n.-- Siskiyou Co. , CA (HT: NY!; IS: US!)
R. rivalis Eastw., Bull. Torrey Bot. Club 32: 198. 1905: Eastwood s.n.-- Laytonville [see discussion in Rydb., 1917]

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