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FNA | Family List | FNA Vol. 9 | Rosaceae | Rubus

17. Rubus leucodermis Douglas ex Torrey & A. Gray, Fl. N. Amer. 1: 454. 1840.

Rubus occidentalis Linnaeus subsp. leucodermis (Douglas ex Torrey & A. Gray) Focke

Shrubs, 10–30 dm, armed. Stems ˂biennial˃, ascending, often arching, glabrous or sparsely puberulent, eglandular or sparsely to densely short-stipitate-glandular, strongly pruinose; prickles moderate to dense, erect or curved, slender to stout, 4–8 mm, usually broad-based, sometimes narrow-based. Leaves deciduous, palmately compound or ternate; stipules filiform, 5–10 mm; ˂petiole with hooked or erect prickles, glabrous, eglandular or sparsely to densely sessile- to short-stipitate-glandular; lateral leaflets stalked, at least 2 larger ones, often with prickles, glabrous, eglandular or stipitate-glandular˃; leaflets 3–5(–7), terminal ovate to lanceolate, 6–10 × 3–6 cm, base cordate to truncate, unlobed or shallowly 3-lobed, margins serrate to doubly serrate, apex acuminate, abaxial surface sometimes with prickles on midrib and some lateral veins, glabrous to strongly white-tomentose, usually eglandular. Inflorescences axillary and terminal, (1–)3–10(–12)-flowered, flat-topped cymiform or umbelliform. Pedicels: prickles sparse to dense, hooked or erect, puberulent, eglandular or sparsely to densely sessile- or short-stipitate-glandular. Flowers bisexual; petals ˂erect, then ascending˃, white, oblong to oblanceolate, 3–6(–8) mm; filaments laminar; ovaries pubescent, rarely glabrous. Fruits reddish purple to nearly black, depressed globose to conic, 1–2 cm; drupelets 20–60, coherent, separating from torus. 2n = 14.

Varieties 2 (2 in the flora): w North America, n Mexico.

Rubus leucodermis is similar to R. occidentalis, differing primarily by its leaflets having acuminate apices and lateral leaflets that are distinctly stalked. Prickles on the pedicels of R. occidentalis are erect; those of R. leucodermis tend to be hooked.

1 Leaves abaxially white-tomentose; drupelets (20–)30–60.   17a Rubus leucodermis var. leucodermis
+ Leaves abaxially glabrous, rarely sparsely hairy; drupelets 20–40.   17b Rubus leucodermis var. nigerrimus

Lower Taxa


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