Article (magazine)  (Jan 2022)  Page(s) 10-11, 14.  Includes photo(s).
 
p. 10: Away from streams, on dry hillsides among chaparral, and also in shady woods, is where California’s little Ground Rose, R. spithamea grows. Its dusty grey-purplish leaves are aptly described as “round, toothy leaflets like gear wheels.”... spithameas have bristles all over pedicel, hip and sepals...
There’s also a rare red-leaved form of R. spithamea we discovered in 1986 with the same whimsical “gear wheels” leaflets but solitary flowers and abundant reddish prickles. It was growing on the crest of the Mayacmas Mountains between the wine growing regions of Napa Valley and Sonoma County....

p. 14: .... R. granulata. (Today it’s considered a synonym of R. spithamea.)...This species has spiked glands (short sharp points) on the underside of its leaves (an obscure character) but the source of Greene’s “granulata” epithet. Botanists suspect R. granulata intergrades with R. californica. ....

Website/Catalog  (2018)  
 
Rosa spithamea S. Watson in W. H. Brewer et al., Bot. California. 2: 444. 1880.
Coast ground rose
Rosa granulata Greene; R. sonomensis Greene; R. spithamea var. sonomensis (Greene) Jepson
Description...
E. W. Erlanson (1934) referred to Rosa spithamea as tetraploid (2n = 28); twice in her key to R. spithamea she questioned that count.

Article (newsletter)  (Aug 2014)  Page(s) 2-4.  Includes photo(s).
 
Rosa spithamea, also called the California “Ground Rose,” (though that nickname could apply equally to R. bridgesii and R. pinetorum) grows in scrub oak and chaparral country from northern Monterey and southern San Luis Obispo counties in the central western to northwestern parts of the state. Near where I live, I have seen it on Ring Mountain above Corte Madera in Marin County and in the hills of Swett Ranch Open Space, a few miles east of Vallejo along the Pacific Ridge Trail in Solano County. In the latter location I have studied it for three years now.
As its name suggests, it is a low growing rose, no more than twelve inches tall. Most of what grows out of a rocky bank immediately below a stand of oak trees where I observe it is no more than a span—six inches high (spithama is Latin for “handspan”). Sometimes among filaree, ferny achillea leaves, wild mint, poison oak, and other understory vegetation, the dwarf plants can be hard at first to spot, especially when not in flower.
Reportedly it blooms with some enthusiasm after a fire, but otherwise it proclaims itself as a reluctant or stingy bloomer. However, in Oregon’s southern Cascades on the south flank of Abbott Butte, hundreds of blossoms have been observed ankledeep. Indeed, my experience has been that, compared to California’s shot glass, Oregon’s botanical cup runneth over.
Rosa spithamea produces single blossoms, lightly scented, of a medium pink (in other locales it may be deep rose or even merely a blush), the size of a quarter or slightly larger. While old grey stems generally display no prickles, the younger green stems bear prickles and bristles that are dark, fine, and essentially straight. Infrastipular spines are not uncommon. Leaves consist of five, seven, and nine leaflets, but mostly seven. They are sessile and broadly serrate, ovate when young, more rounded when mature. Like raised wings, the first set of leaflets below the apical leaflet point upward. Stipules are glandular-ciliate (i.e., with tiny hairy glands), auricles widespread. The receptacle is distinctive: densely pilose, that is, covered with straight glandular hairs. Underground suckering roots can make it slowly pervasive.
If one looked at the five pink petals alone, the flower might easily be mistaken for nearly any other California wild rose. But location aside, we can distinguish a few traits from some of the others. R. gymnocarpa, not a crawler, tends to grow erect and even as tall as four feet, generally in part shade beneath redwood or oak trees. It also drops its ovate sepals and, unlike R. spithamea, exudes a strong fragrance. Rosa pinetorum, on the other hand, found under Monterey pines, bears a glabrous receptacle, that is, one without hairs. And R. bridgesii exhibits few prickles and produces roses only in small clusters of two or more and stipules that are ciliate, i.e., with distinct hairs or glands. According to botanist Barbara Ertter, it appears to grow no hips.
Could Rosas spithamea, pinetorum, and bridgesii, all three ground roses and genetically tetraploid, be subspecies of R. gymnocarpa, a diploid? Possibly. According to rose species authority Cassandra Bernstein, “Widely distributed diploid plant species that spread into extreme environments”— and R. gymnocarpa can be found from the understory of redwoods to the understory of oaks, from the Sierra Nevada foothills to the Pacific coast —“have been known to mutate, evolve, or hybridize into different ploidies than those commonly reported.” Surely, then, the three ground rose species may be the same rose whose ecogeographic variations have created variations in the species.
If botanist Daniel Chamovitz is correct that environmental stress in a plant seems to cause “a heritable change that is passed on to successive generations,” then one or more of these California species could be morphologically one with R. gymnocarpa. Small variations in a species may be the result of environmental stress— drought, severe rainfall, fire, pestilence, salt in air or soil. In fact, claims Chamovitz, “different environmental insults increase the frequency of genomic rearrangements” in plants of both parental and second generations, the latter showing further genetic alteration but more tolerance to stress, often proving themselves more hardy or vigorous in harsh environmental situations. Rosa spithamea. One could then, without DNA evidence, draw the conclusion that to speak or write of the varieties of R. spithamea is to nick-pick or to split hairs. Whether in one county its prickles are broader at the base and in another its prickles are nearly absent, these may be mere environmental distinctions, not characteristics that identify and define this span-high ground rose. And whether it is a subspecies of R. gymnocarpa or a species in its own right, Rosa spithamea is variable. Though it can be found growing from rocky outcrops, it—like many species—is not set in stone.

Article (website)  (2007)  
 
Subgenus Rosa, Section Gymnocarpae: Wood and Ground Roses

Rosa spithamea S. Watson
Low growing, most likely to flower after fires; blooms several to a cluster; many stalked glands on the receptacle and sepals; many straight prickles; 6 to 24 inches tall; round hips with persistent sepals; native to north and central coast ranges from Monterey north, Siskiyou Mountains. Blooms April to August especially where recently burned.

Article (misc)  (1965)  Page(s) 159.  
 
Tetraploid (2n=28) R. spithamea

Book  (1944)  Page(s) 463.  Includes photo(s).
 
Rosa spithamaea S. Wats. Ground Rose. Fig. 2516.
Rosa spithamaea S. Wats. Bot. Calif. 2: 444. 1880.
Rosa adenocarpa Greene, Leaflets Bot. Obs. 2: 261. 1912.

Stems low, 1-3 dm. high, from creeping rootstocks, armed with straight, terete, infrastipular prickles and often also bristly. Stipules glandular-ciliate and slightly glandular on the back; petioles and rachis glandular and often with a few prickles ; leaflets usually 5, oval to sub-orbicular, 1-3 . 5 cm. long, doubly serrate with gland-tipped teeth, sparingly pubescent or glabrate above, glandular-pruinose beneath; flowers corymbose or sometimes solitary; pedicels glandular-hispid ; hypanthium ellipsoid or subglobose, densely glandular-hispid, 7-8 mm. broad in fruit ; sepals densely glandular-hispid on the back.
Open forests, Arid Transition Zone; southwestern Oregon and northwestern California. Type locality: Trinity River, California. June-Aug.

 

Book  (1939)  Page(s) 179.  
 
Key to the Species
Sepals, styles and upper part of the hypanthium persistent on the fruit; pistils numerous.
- Hypanthium densely glandular or glandular-hispid or bristly.
-- Stems with stout (rarely slender) prickles ¼- to ½-inch long, usually straight, more or less flattened below, often ascending; petals ¾-inch to 1½ inches long......1a. R. nutkana var. hispida.
-- Stems with few slender usually straight prickles, sometimes with many additional bristles; sepals without foliaceous tips; petals ½- to ¾-inch long.....2. R. spithamea.

Book  (1939)  Page(s) 181-182.  
 
Rosa spithamea Wats. Ground Rose. Fig. 192.
Key to the species and variety
Leaflets thin, usually more than 5/8-inch long; stems with few slender straight prickles...R. spithamea.
Leaflets firm, less than 5/8-inch long, glaucous beneath; stems armed with numerous stoutish straight or recurved prickles....var. sonomensis.
A low sparingly branched shrub, ½-foot to 1 foot high, usually armed with bristlesand slender straight pricklesor sometimes almost unarmed. Leaflets 3 to 7, usually 5, oval or almost round, ¼-inch to 1¼ inches long, glabrous and green (or rarely slightly pubescent above), sometimes almost green but usually paler and somewhat glandular-waxy and pubescent (not glandular) beneath, doubly serrate with glandular teeth; petioles and rachises more or less glandular; stipules glandular on the margins. Flowers rose-pink, solitary or few to several in terminal clusters; pedicels with gland-tipped hairs; sepals ¼- to ½-inch long, usually without foliaceous tips, glandular-hairy on the back, persistent on fruit; petals obcordate, ½-inch to rarely 1 inch long; hypanthium in fruit subglobose, ¼- to ½-inch long, glandular-hairy or densely glandular-bristly. Flowering period May to July.
Ground Rose occurs in open woods of the North Coast Ranges from Humboldt and Trinity counties southward to Mendocino and Lake counties where it becomes intermediate with the variety, and in the Sierra Nevada from Tulare County to Mariposa County, in the Transition Life Zone....
Rosa spithamea Wats. Bot. Calif. 2:444 (1880). Type locality: Trinity River, California. Collected by Rattan.

Book  (1909)  Page(s) 211, Vol. 2.  
 
R. spithamea Wats. Ground Rose.
About 1 foot high; prickles few, straight; leaves minutely pubescent; grassy slopes in open wood 600 to 4000 feet. North Coast Range. Sierra Nevada [this is now separated into R. bridgesii}

Article (magazine)  (1897)  Page(s) 155.  
 
R. spithamea Wats.

a. Feuille. — Poils simples rares ou nuls sur le limbe, plus nombreux sur le pétiole. Poils glandulifères sur les deux épidémies ou seulement sur l'inférieur, ainsi que sur le pétiole. Épiderme supérieur recticurviligne, d'une épaisseur de 28-29 μ, à cellules très grandes ou moyennes. Épiderme inférieur d'une épaisseur de 11-16 μ, onduleux ou subonduleux, à cellules très grandes. Stomates d'une longueur de 30-34 μ, plus petits que les cellules environnantes. Mésophylle bifacial, d'une épaisseur de 90-135 μ, composé de 5-7 assises, les 2-4 supérieures transformées en palissades remplissant 2/3 de l'épaisseur totale. Parenchyme spongieux lacuneux, à cellules courtes, ovales et irrégulièrement disposées ou à cellules allongées horizontalement. Faisceaux des nervures et du pétiolule pourvus de fibres péridesmiques.

b. Tige. — Cuticule épaisse; parenchyme cortical composé de 13-19 assises de cellules ordinairement peu allongées tangentiellement. Bois très vasculaire. Vaisseaux ordinairement petits. Moelle à cellules moyennes ou petites.