Native California Roses

copyright Barbara Ertter, 2001
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Rosa spithameaS. Watson
"Coast Ground Rose"

Description Distribution Discussion Horticultural Notes Nomenclature Links

open low-growing plants, most common after fires prickles often numerous; flowers several hips and sepal with abundant stalked glands line drawing

DESCRIPTION: Openly rhizomatous dwarf shrub, generally < 5 dm tall. Stem gray-brown; prickles few to many, slender, straight (to slightly curved). Leaf 3--10 cm long; stipule margins with distinct glands; leaflets 2--3(4) per side, glabrous to sparsely hairy; terminal leaflet generally 10--30 mm long, widely elliptic (obovate), the base obtuse, the tip obtuse to truncate; leaf-margins generally double-toothed, glandular. Inflorescence (1)2--5(10)-flowered; pedicels generally 5--15 mm long, generally glandular, rarely glabrous. Flowers: body of hip in flower generally 4--5 mm wide, stalked-glandular (usually densely so), neck of hip generally 3--4 mm wide; sepals generally glandular, the margins entire, sepal-tip generally equalling or shorter than sepal-body, entire; petals generally 10--15 mm long; pistils 10 or more in number. Hip usually globose, 7--10 mm wide, stalked-glandular, neck 4--5 mm wide, sepals persistent. Blooming April to August. Openings in forest and chaparral, especially where recently burned; 150--2000 m elev.

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Northwestern and west-central California to northern Monterey Co., and apparently disjunct in San Luis Obispo Co.; southwestern Oregon.

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

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DISCUSSION: Rosa spithamea is the "classic" ground rose, averaging only about a foot tall and spreading widely by underground rootstocks. Prickles are slender, relatively straight, and often numerous, and the hips are distinctively covered with stalked glands (a characteristic otherwise found only in some forms of R. nutkana, and rarely R. bridgesii, among native California roses). Previous references to Rosa spithamea from the Sierra Nevada are largely based on what is currently treated as R. bridgesii.

The primary distribution of the coast ground rose as currently understood is in the North Coast Ranges, extending south to northern Monterey County and north to southwestern Oregon. An apparently disjunct cluster of populations in the Los Osos region of San Luis Obispo County has certain peculiarities, specifically a tendency to have significantly thicker prickles and only sporadically glandular hips, perhaps intergrading with R. californica. As noted by Hoover (1966, Leafl. W. Bot. 10: 337--350), plants from this area "constituted a uniform population, identical in all respects except that some had the receptacle entirely devoid of glands while others showed sparse to dense glands." Because these are only tendencies rather than clear-cut distinctions, the best taxonomic placement of these plants is still unclear. The type of Rosa granulata Greene is representative of this form.

Images of the San Luis Obispo extreme
Chaparral habitat of disjunct San Luis Obispo population Atypically thickened prickles on San Luis Obispo plants

Previous treatments have generally recognized two varieties within R. spithamea, with var. sonomensis having more prickles than the typical var. spithamea. I was unable to justify maintaining the two varieties based on the material available to me at the time I was preparing the treatment for The Jepson Manual (see Historical Background), and accordingly lumped both together. One result of subsequent studies, however, has been the realization that populations from northwestern California, as represented by the type specimen, are in fact notably less prickly than those from further south, lessening the differences between the Coast Ground Rose and Sierra Ground Rose. In fact, it may be that R. spithamea and R. bridgesii are botanical counterparts of the well-known "ring species" salamanders, in which one extreme form in the south Coast Ranges intergrades in northern California to another extreme that is best developed in the southern Sierra Nevada. Needless to say, more study is called for.

Rosa spithamea is apparently a member of California's well-known fire-following flora, with a twist. Plants persist between fires not as seeds but as inconspicuous, rarely flowering members of the scrub or forest understory. In this stage they are routinely mistaken for depauperate Rosa gymnocarpa, which is overall more common, but even vegetative plants can generally be recognized (with some practice) by the consistently shorter stature and relatively blunter, fewer leaves, which often turn strikingly scarlet in fall. Apparently only after fire removes the overstory, and covers the ground with nutrient-rich ash, does Rosa spithamea flourish and put on a prominent display of abundant flowers.

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HORTICULTURAL NOTES: The short habit and colorful fall foliage of the Coast Ground Rose suggest significant horticultural potential, but the possible fire requirement might be at odds the average gardening regime.

Leaves turning crimson in fall

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R. spithamea S.Watson, Bot. Calif. 2: 444. 1880: Rattan s.n.--Trinity River

Possible Synonyms (working list):
R. adenocarpa Greene, Leafl. Bot. Observ. Crit. 2: 261. 1912: Piper s.n., Mt Grayback in SW OR, 15 Jun 1904 (HT: US527765!; fragment at NY!) [hips of spithamea, but prickles and leaflet shape of bridgesii]
R. amplifolia Greene, Leafl. Bot. Observ. Crit. 2: 258. 1912: Applegate s.n.--Fish Lake, Jackson Co, OR, 18 Jun 1898 (HT: US381523!) [unusually large leaflets]
R. boland[e]ri Greene, Leafl. Bot. Observ. Crit. 2: 261. 1912: Bolander--Oakland Hills (HT: US45934!; IS: US!) = spithamea X gymnocarpa? [sepals persistent but hips glabrous, aspect of spithamea]
R. granulata Greene, Leafl. Bot. Observ. Crit. 2: 262. 1912: Brewer--San Luis Obispo Co., Apr 1861 (HT: US320920; fragment at NY!) [exceptionally thick prickles]
R. sonomensis Greene, Fl. Franciscana 72. 1891: Greene, Sonoma Co., Petrified Forest, 1883 (NY!) = spithamea

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