(Aug 2014)  Page(s) 4.  
 
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.

(Aug 2014)  Page(s) 3.  
 
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.....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.

(Aug 2014)  Page(s) 4.  
 
Rosa pinetorum, on the other hand, found under Monterey pines, bears a glabrous receptacle, that is, one without hairs.....
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.

(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.