Native California Roses

copyright Barbara Ertter, 2001
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Rosa pinetorum A.A. Heller
"Pine Rose"

Description Distribution Discussion Horticultural Notes Nomenclature Links

Habitat in open understory of native Monterey Pine (Pinus radiata) forest. Stems relatively short, scattered, not thicket-forming. Prickles abundant, straight; hips glabrous. Flowers solitary or few; leaves single- or double-toothed. Line drawing.

DESCRIPTION: Dwarf ± rhizomatous shrub, generally < 10 dm tall. Stem gray-brown; prickles generally many, both slender and ± thickened, straight. Leaf: stipule margins with distinct glands; leaflets 2--3 per side, glabrous to sparsely hairy; terminal leaflet ± 10--40 mm long, generally ± elliptic, the base ± obtuse, the tip ± obtuse; leaf-margins most often ± double-toothed, ± glandular. Inflorescence generally 1--5-flowered; pedicels generally 10--30 mm long, glabrous to glandular. Flowers: body of hip in flower generally ± 4 mm wide, glabrous, neck of hip ± 3 mm wide; sepals generally ± glandular, sepal-tip generally ± equal in length to sepal-body, entire or toothed; petals ± 15--20 mm long; pistils ± 10--20 in number. Hip generally globose, ± 12 mm wide, glabrous, neck 1.5--4 mm wide, sepals persistent. Blooming June to August. Understory of open Pinus radiata woodlands, canyons; generally < 300 m elev.

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DISTRIBUTION OF ROSA PINETORUM:
As currently treated, the Pine Rose is apparently restricted to the open understory of native stands of Monterey Pine (Pinus radiata) from the Monterey Peninsula to Carmel Highlands, Waddell Creek near Año Nuevo State Park, and possibly Cambria as well.
(NOTE: This distribution reflects a radically reduced circumscription of R. pinetorum as compared to most previous treatments. See R. bridgesii for Sierran material referred to by this name.)

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

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DISCUSSION: The circumscription of Rosa pinetorum as given here, and in The Jepson Manual, differs dramatically from most previous treatments, with R. bridgesii now used for plants from the Sierra Nevada formerly referred to as R. pinetorum. As interpreted by Munz (A California Flora, 1959), R. pinetorum occurred from northern California south to Monterey County in the Coast Ranges, and in the Sierra Nevada south to Tulare County. However, while preparing my treatment of Rosa for The Jepson Manual (see Historical Background), by the time I had identified and sorted out all the specimens that fit my understanding of Rosa bridgesii, R. spithamea, and R. gymnocarpa, I was left with only a small residue of specimens. This residue included the type collection of Rosa pinetorum, which is why this name could no longer be used for the Sierra Nevada plants. The handful of specimens were all apparently from native Monterey pine forests, mostly from the Monterey Peninsula to Carmel Highlands, but also from Waddell Creek near Año Nuevo State Park, and possibly from Cambria as well. In other words, whereas Rosa pinetorum sensu Munz was a relatively common and widespread species, Rosa pinetorum sensu Ertter is a highly localized and possibly endangered plant.

To further complicate the situation, the handful of populations currently identified as Rosa pinetorum exhibit greater morphological variation than would be logically expected in a single localized species. As a generality, plants are of medium height, with abundant straight prickles (both slender and thick-based) and multiple flowers with glabrous hips and pedicels. Significant variation occurs even on the Monterey Peninsula, with flower color ranging from light pink to nearly red, and prickles likewise varying in thickness. Plants from Cambria differ further in being relatively tall, and in fact approach the thicket-forming habit. Further studies are obviously called for, with one possibility being that the pine rose might have more in common with R. nutkana than with the other ground roses.

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HORTICULTURAL NOTES: The diverse variation within the Pine Rose provides good material from which to select horticulturally desirable forms, with the extra incentive of propagating a very uncommon species.

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NOMENCLATURE:
R. pinetorum Heller, Muhlenbergia 1: 53. 1904: Heller 6817--Pacific Grove (HT: BKL! in NY!; IS: NY!)

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LINKS:

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