Rubus nivalis
Rubus pensilvanicus
dwarf snow bramble, snow bramble, snow dewberry, snow dwarf bramble, snow raspberry
Pennsylvania blackberry, ronce de pennsylvanie
perennial, creeping, sparsely hairy, glabrescent, eglandular, not pruinose;
prickles sparse, strongly retrorse, stout, to 1 mm, broad-based.
biennial, erect to arching, glabrous or sparsely to densely hairy, eglandular or sparsely to moderately, rarely densely, sessile- to short-stipitate-glandular, not pruinose;
prickles sparse to dense, erect or slightly retrorse, stout, 4–10 mm, broad-based.
evergreen, simple or ternate;
stipules adnate to petioles, broadly elliptic to ovate, (6–)8–10 mm;
blade ovate to cordate, (2.5–)3–5(–8) cm, lobe or leaflet base cordate, shallowly 3-lobed, margins coarsely, singly or doubly dentate, apex acute to obtuse, abaxial surfaces with prickles along midveins, glabrous or sparsely hairy, eglandular, both surfaces lustrous fresh.
deciduous, palmately compound, not lustrous;
stipules filiform to narrowly lanceolate, (3–)5–15(–20) mm;
leaflets (3–)5(–7), terminal ovate to lanceolate, 5–15 × 3–13 cm, base rounded to shallowly cordate, unlobed, margins finely to coarsely singly or doubly serrate, apex acuminate to long-attenuate, abaxial surfaces green, usually with retrorse prickles on midveins, moderately hairy, eglandular or sparsely to moderately sessile- to short-stipitate-glandular along veins.
1–2-flowered.
terminal on short shoots, usually appearing axillary, (2–)5–12(–16)-flowered, cymiform, racemiform, or thyrsiform.
prickles scattered, retrorse, moderately to densely hairy, eglandular.
unarmed or prickles sparse, erect, glabrous or sparsely to densely hairy, eglandular or sparsely to moderately sessile- to short-stipitate-glandular.
bisexual;
petals magenta to pink, elliptic to oblanceolate or spatulate, (5–)8–10 mm;
filaments filiform;
ovaries moderately hairy, styles glabrous.
bisexual;
petals white, usually obovate to elliptic, rarely suborbiculate, 8–40 mm;
filaments filiform;
ovaries glabrous.
red, hemispheric, 0.4–1 cm;
drupelets 3–10, not coherent, separating from torus.
black, globose to cylindric, 1–2 cm;
drupelets 10–100, strongly coherent, separating with torus attached.
= 14.
= 14, 21, 28, 35, 36, 42.
Rubus nivalis
Rubus pensilvanicus
Rubus nivalis is recognized by its creeping, prickly stems, simple to ternate, evergreen leaves, broadly elliptic to ovate stipules, two leaflets, relatively small flowers, and magenta to pink petals. Its closest relative is likely the Mexican R. pumilus Focke. Asian species previously classified in subg. Chamaebatus (Focke) Focke are hexaploid (M. M. Thompson 1997) and not phylogenetically close; R. nivalis appears to be sister to all blackberries of subg. Rubus (L. A. Alice and C. S. Campbell 1999; Alice et al. 2008).
The fruits of Rubus nivalis are eaten fresh, stewed, and canned by the Hoh and Quileute Indians (A. B. Reagan 1936).
The only known specimen of Rubus nivalis from California was collected in 1961 from Del Norte County at 1250 m near the Oregon border.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
As circumscribed here, Rubus pensilvanicus represents sect. Arguti (L. H. Bailey) L. H. Bailey, in which Bailey (1941–1945) recognized 109 species.
More strongly glandular plants of Rubus pensilvanicus may represent introgression with R. allegheniensis or other species, especially when exhibiting long-stipitate glands. Thyrsiform inflorescences are present in plants that have been called R. missouricus. There are reports (T. S. Mallah 1954; L. V. Clark and M. Jasieniuk 2012; B. Sutherland and L. A. Alice, unpubl.) of R. pensilvanicus hybridizing with R. ursinus.
Rubus pensilvanicus is introduced in California, Idaho, and Washington.
The following nothospecies names are based on putative hybrids involving Rubus pensilvanicus and: R. allegheniensis (R. ×avipes L. H. Bailey, R. ×floricomus Blanchard, R. ×orarius Blanchard); R. canadensis (R. ×amabilis Blanchard [not Focke], R. ×amicalis Blanchard, R. ×elegantulus Blanchard [=R. canadensis var. elegantulus (Blanchard) Farwell], R. ×multilicius L. H. Bailey, R. ×noveboracus L. H. Bailey, R. ×pergratus Blanchard [= R. canadensis var. pergratus (Blanchard) L. H. Bailey], R. ×crux Ashe); R. cuneifolius (R. ×acer L. H. Bailey, R. ×acer var. subacer L. H. Bailey, R. ×argutinus L. H. Bailey, R. ×floridensis L. H. Bailey); R. flagellaris (R. ×akermanii Fernald, R. ×darlingtonii L. H. Bailey, R. ×dissitiflorus Fernald, R. ×hypolasius Fernald, R. ×janssonii L. H. Bailey, R. ×largus L. H. Bailey, R. ×recurvicaulis Blanchard, R. rossbergianus Blanchard); R. setosus (R. ×wisconsinensis L. H. Bailey).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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