Rubus ulmifolius
Rubus trivialis
elm-leaf blackberry
southern 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, initially low-arching, then falling and creeping (or climbing through other vegetation), glabrous or moderately hairy, sparsely to densely short- to long-stipitate-glandular, not pruinose;
prickles moderate to dense, recurved, sometimes distally slender, 1–4 mm, broad-based;
bristles absent or sparse to dense, erect to retrorse, red to purple, rarely green, slender, weak, gland-tipped.
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.
persistent or semipersistent, ternate to palmately compound, lustrous;
stipules filiform, linear, or lanceolate, 2–12(–15) mm;
leaflets 3–5, terminal narrowly elliptic or ovate to obovate, 2–8.5 × 0.7–4.5 cm, base rounded to cuneate, unlobed, margins moderately to coarsely serrate to doubly serrate, apex acute to acuminate, abaxial surfaces with hooked prickles on midvein, glabrous or sparsely to moderately hairy, eglandular or sparsely short-stipitate-glandular along central vein.
terminal, 10–60-flowered, paniculiform or thyrsiform.
terminal on short shoots, usually appearing axillary, 1(–3)-flowered.
unarmed or prickles moderate to dense, erect to hooked, densely short-hairy, eglandular.
prickles and, often, bristles moderate to dense, recurved, moderately to densely hairy, sparsely to moderately sessile- to short-stipitate-glandular.
bisexual;
petals usually pink, sometimes white, obovate or elliptic to suborbiculate, 5–12 mm;
filaments filiform;
ovaries apically hairy.
bisexual;
petals white to pink, elliptic to obovate, 10–16(–25) mm;
filaments filiform;
ovaries glabrous.
black, globose to ovoid, 1–1.5 cm;
drupelets 10–40, strongly coherent, separating with torus attached.
black, globose to ovoid, 1–1.5(–2) cm;
drupelets 10–50, strongly coherent, separating with torus attached.
= 14.
= 14.
Rubus ulmifolius
Rubus trivialis
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 trivialis is distinguished from other species of Rubus by its frequently glandular-bristly and generally creeping stems, abundant recurved prickles, and typically persistent or semipersistent, lustrous primocane leaves with relatively narrow leaflets. Although emerging primocanes typically reach to 30 cm above the ground, vigorous plants can have new primocanes standing erect to 70 cm that later fall to the ground or onto adjacent vegetation as they continue to enlarge. L. H. Bailey (1941–1945) believed that there was no clear separation between members of sect. Persistentes Fernald (referred to by Bailey as sect. Verotriviales [illegitimate sectional name for R. trivialis and associated species]) and sect. Procumbentes (by Bailey as sect. Flagellares; including R. flagellaris and related species). All characteristics that he recognized for distinguishing sect. Persistentes from sect. Procumbentes are often present in the latter, with the exception of hispid-setose stems, and glabrous plants of R. trivialis are difficult to distinguish from some plants of R. flagellaris; to include the latter species within the former would be reasonable.
Rubus ×inferior L. H. Bailey is a putative hybrid of R. trivialis and R. cuneifolius.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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