Rubus nutkanus
Rubus cuneifolius
thimbleberry
sand blackberry
biennial, erect, sparsely hairy, glabrescent, moderately stipitate-glandular, glands yellowish to reddish, not pruinose.
biennial, erect, rarely arching, sparsely to densely hairy (especially young), eglandular, not pruinose;
bark not papery, peeling;
prickles usually dense, hooked to retrorse, usually stout, 3–6 mm, broad-based.
deciduous, simple;
stipules lanceolate to ovate, 5–15 mm;
blade orbiculate to reniform, 5–20 × 5–25 cm, base cordate, palmately, shallowly to moderately deeply, (3–)5(–7)-lobed, margins coarsely, irregularly serrate to doubly serrate, apex shortly acuminate to obtuse, abaxial surfaces glabrate to densely hairy, sparsely to moderately stipitate-glandular, glands yellowish to reddish.
deciduous to semievergreen, usually ternate, sometimes palmately compound;
stipules filiform or linear to lanceolate, 3–15 mm;
leaflets 3–5, terminal cuneate to obovate, 2–6 × 3–4 cm, base cuneate, unlobed, margins serrate, rarely doubly serrate, apex broadly rounded to subtruncate, often cuspidate, abaxial surfaces often with prickles on midveins, densely gray- to white-hairy, sparsely to densely sessile-glandular.
terminal and axillary, (1–)3–7(–15), cymiform to thyrsiform.
terminal on short shoots, sometimes appearing axillary, (1–)3–5(–12)-flowered, cymiform.
sparsely to moderately hairy, moderately to densely stipitate-glandular, glands yellowish to reddish.
unarmed or prickles sparse to moderate, hooked to retrorse, moderately to densely hairy, eglandular or sparsely to moderately sessile-glandular.
bisexual;
petals white, broadly obovate, (10–)14–22(–28) mm;
filaments filiform;
ovaries distally densely hairy, styles clavate, glabrous.
bisexual;
petals white, elliptic to obovate, 5–15 mm;
filaments filiform;
ovaries glabrous or glabrate.
red, hemispheric, 1–1.8 cm;
drupelets 50–60, coherent, separating from torus.
black, globose to cylindric, 0.6–2 cm;
drupelets 15–50, strongly coherent, separating with torus attached.
= 14.
= 21, 28.
Rubus nutkanus
Rubus cuneifolius
Rubus nutkanus is distinguished from other flowering raspberries by its erect, unarmed stems, simple leaves, large flowers, white petals, glabrous, clavate styles, and yellowish to reddish stipitate glands covering most plant parts. A hybrid with R. odoratus (R. ×fraseri Rehder) is thought to occur in areas of overlap in northern Michigan (E. G. Voss 1972–1996, vol. 2). Varieties and forms have been described based on indument and glandularity of stems, leaves, petioles, pedicels, and sepals (for example, M. L. Fernald 1950). Different variants often occur mixed in the same population and generally do not correspond to definite geographic regions (N. C. Fassett 1941). Plants from coastal California (considered as var. velutinus) tend to have densely hairy leaf abaxial surfaces; this variation may be environmentally induced; other Rubus species show the same pattern (for example, R. spectabilis var. franciscanus) in that area. Wild thimbleberries are collected in Keweenaw Peninsula, Michigan, and are used in beverages and especially for jam.
Rubus nutkanus is typically associated with western North America but was originally described from plants at its eastern range limit in northern Michigan. The Great Lakes populations are disjunct from western mountain populations by around 600 miles.
The name Rubus parviflorus var. grandiflorus Farwell, which applies here, is illegitimate.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Rubus cuneifolius is characteristic of the Coastal Plain and Piedmont. The species is distinguished from most other blackberries in the flora area by its usually strongly erect and shrub-forming habit and abaxial leaflet surfaces often with dense white to gray indument; it may be confused with R. pascuus. Rubus cuneifolius has white petals and cuneate to obovate leaflets with usually revolute margins, the proximal third entire; R. pascuus has pale pink to white petals and ovate to broadly elliptic leaflets with the margins flat and entire only at base.
Rubus longii Fernald may represent hybridization between R. cuneifolius and another, yet-undetermined, blackberry (perhaps R. pascuus). Hybrids of R. cuneifolius and R. hispidus can be found around abandoned commercial cranberry bogs in New Jersey (G. Moore, pers. obs.). Rubus cuneifolius is introduced in South Africa and is officially recognized there as a noxious weed (L. Henderson 1995; T. Olkers and M. P. Hill 1999; H. Klein 2002). Preliminary examination of plants identified as R. cuneifolius from South Africa has shown that the plants are not R. cuneifolius but may be hybrids involving R. cuneifolius and another species.
The following nothospecies names are based on putative hybrids involving Rubus cuneifolius and: R. pensilvanicus (R. ×acer L. H. Bailey, R. ×acer var. subacer L. H. Bailey, R. ×argutinus L. H. Bailey, R. ×floridensis L. H. Bailey); R. trivialis (R. ×inferior L. H. Bailey).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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