Rubus ulmifolius
Rubus flagellaris
elm-leaf blackberry
northern blackberry, northern dewberry, ronce à flagelles, whiplash dewberry
biennial, erect, then arching, usually moderately, rarely sparsely, hairy hairs stellate, eglandular, strongly pruinose;
prickles absent or sparse to dense, erect to hooked, stout, 3–10 mm, broad-based.
biennial, usually creeping, sometimes low-arching and then creeping flowering branches usually erect, glabrous or densely hairy, eglandular or sparsely sessile- to short-stipitate-glandular, not pruinose;
prickles sparse to dense, hooked, sometimes distally slender, 1–4 mm, broad-based;
bristles absent.
persistent or nearly so, ternate to palmately compound;
stipules filiform to linear, 4–12 mm;
leaflets 3–5, terminal ovate, elliptic, or suborbiculate to obovate, 4–10 × 2–6(–9) cm, base rounded to cuneate, unlobed, margins finely to moderately serrate, apex acute or acuminate to attenuate, abaxial surfaces with hooked prickles on larger veins, densely white short-velutinous, hairs usually minute, eglandular.
deciduous, some sometimes semipersistent, ternate or palmately compound, not lustrous;
stipules filiform or linear to lanceolate, 3–20 mm;
leaflets 3–5, terminal ovate or elliptic to suborbiculate, 3–11 × 2–7.5 cm, base broadly cuneate or rounded to shallowly cordate, usually unlobed, rarely shallowly lobed, margins moderately to coarsely serrate to doubly serrate or serrate-dentate, apex acute or acuminate to short-attenuate, abaxial surfaces with prickles on midvein or unarmed, sparsely to moderately hairy, eglandular or sessile- or short-stipitate-glandular along largest veins.
terminal, 10–60-flowered, paniculiform or thyrsiform.
terminal on short shoots, usually appearing axillary, 1–3(–8)-flowered, racemiform.
unarmed or prickles moderate to dense, erect to hooked, densely short-hairy, eglandular.
unarmed or prickles sparse to moderate, retrorse to hooked, moderately to densely hairy, usually sparsely to densely sessile- or short-stipitate-glandular, rarely eglandular.
bisexual;
petals usually pink, sometimes white, obovate or elliptic to suborbiculate, 5–12 mm;
filaments filiform;
ovaries apically hairy.
bisexual;
petals white, elliptic, obovate, or oblanceolate, 8–20 mm;
filaments filiform;
ovaries glabrous.
black, globose to ovoid, 1–1.5 cm;
drupelets 10–40, strongly coherent, separating with torus attached.
black, sometimes dark red, globose to cylindric, 1–2 cm;
drupelets 10–40, strongly coherent, separating with torus attached.
= 14.
= 14, 21, 28, 35, 42, 49, 56, 63.
Rubus ulmifolius
Rubus flagellaris
Rubus ulmifolius can be distinguished, especially from the closely related R. bifrons and R. vestitus, by its strongly pruinose stems, finely serrate leaflets, and lack of glands throughout. Unlike R. ulmifolius, strongly pruinose native Rubus species lack relatively large and showy pink petals. Some new stems developing from tip-rooting, and early leaves on such stems (especially in shade), are not whitened abaxially and are tomentose. Such unusual stems develop typical leaves and surfaces in parts formed later.
There has been nomenclatural confusion over unarmed plants of Rubus ulmifolius (see E. Monasterio-Huelin and H. E. Weber 1996). Rubus inermis Willdenow is an illegitimate later homonym of R. inermis Pourret, and the type specimens for both names are of poor-quality. If an unarmed variety of R. ulmifolius is to be recognized, such as occurs in California, the name var. anoplothyrsus Sudre should be used instead of var. inermis (Willdenow) Focke.
Rubus ulmifolius is attractive and is potentially weedy but relatively uncommon, found primarily in coastal California from the San Francisco Bay region southward. It probably no longer persists in New Jersey, last collected there in 1897, and it is rare in Nevada and Oregon. Rubus ulmifolius likely hybridizes with R. bifrons where they co-occur; it is one of relatively few diploid and sexually reproducing species of European blackberries.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Rubus flagellaris is extremely polymorphic, ranging from plants with low-arching (and later creeping) stems and relatively few prickles to low, creeping plants with abundant prickles. Individual plants in some years will produce abundant, arching, poorly armed stems, and in others creeping, well-armed stems. Prickle shape also varies in these plants both within a year and among different years. Local variants seem to readily intergrade with other variants; over the entire North American range of what would be known as sect. Procumbentes (Rydberg) L. H. Bailey [= sect. Flagellares (L. H. Bailey) L. H. Bailey], a continuum of variation seems to be common. sect. Procumbentes (Rydberg) L. H. Bailey [by Bailey as sect. Flagellares (L. H. Bailey) L. H. Bailey
Apparent consistent features of Rubus flagellaris are terete primocanes to 7 mm diam. near the base and presence of rigid, hooked primocane prickles to 4 mm. Primocanes that tip-root and are low and long-running are nearly consistent features of R. flagellaris. Flower number per inflorescence throughout most of the geographic range of R. flagellaris is one to three or, rarely, five; in the far western part of the range (as R. arizonensis [= R. oligospermus Thornber ex Rydberg, name illegitimate]) up to eight flowers per inflorescence have been reported.
Rubus flagellaris lacks pruinose fruits and stems and is similar in general appearance to the introduced R. caesius.
Rubus vagus L. H. Bailey is an illegitimate later homonym that applies here. Rubus longipes Fernald is an illegitimate name that applies here.
The following nothospecies names are based on putative hybrids involving Rubus flagellaris and: R. allegheniensis (R. ×boyntonii Ashe, R. ×fraternalis L. H. Bailey [based on R. ×fraternus Brainerd & Peitersen (not R. fraternus Gremli)], R. ×licens L. H. Bailey; R. ×ostryifolius Rydberg); R. canadensis (R. ×lepagei L. H. Bailey, R. ×rixosus L. H. Bailey); R. hispidus (R. ×ambigens Fernald, R. ×distinctus L. H. Bailey, R. ×elongatus Brainerd & Peitersen [not R. elongatus Smith], R. ×emeritus L. H. Bailey, R. ×furtivus L. H. Bailey, R. ×kalamazoensis L. H. Bailey, R. ×permixtus Blanchard, R. ×rosendahlii L. H. Bailey, R. ×segnis L. H. Bailey, R. ×varus L. H. Bailey, R. ×vigoratus L. H. Bailey); R. pensilvanicus (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. ×alter L. H. Bailey, R. ×arcuans Fernald & H. St. John, R. ×biformispinus Blanchard, R. ×bigelovianus L. H. Bailey, R. ×bracteolifer Fernald, R. ×jacens Blanchard var. specialis L. H. Bailey, R. ×laevior (L. H. Bailey) Fernald [based on R. permixtus var. laevior L. H. Bailey], R. ×multiformis Blanchard, R. ×setospinosus L. H. Bailey, R. ×severus Brainerd ex Fernald).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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