Rubus plicatifolius Blanchard

Rubus plicatifolius Blanchard, Rhodora 8: 149. 1906
Rubus villoms Ait. Hort. Kew. 2: 210. 1789. Not R. vilhsus Thunb. 1784.
Rubus procumbens Rydb. in Britton, Man. 498. 1901. Not. R. procumbens Muhl. 1818.
Stems biennial, prostrate, 1-2 m. long, greenish or purplish, terete, glabrous or the young parts sparingly appressed-pubescent, not glandular, armed with weak, straight, somewhat retrorse prickles; leaves of the turions 3-5-f oliolate; stipules subulate, about 1 cm. long; petioles, petiolules, and veins with slender retrorse prickles, glabrous or somewhat pubescent beneath; leaflets oval or ovate, abruptly long-acuminate, finely and sharply serrate, plicate, rugose and with strong veins beneath, acute or obtuse at the base; terminal leaflet broad, 7-10 cm. long, its petiolule 1-3 cm. long; lateral leaflets subsessile or short-petioluled; floral branches 1-2 dm. long, pubescent; leaves 3-foliolate or 1-f oliolate; leaflets oval, obovate, or obovatecuneate, 3-5 cm. long, glabrate above but rather densely pubescent beneath; inflorescence a corymb or short raceme, 3-8-flowered, rather densely pubescent, glandless or with a few sessile glands; sepals 5-6 mm. long, ovate, caudateacuminate, villous without, tomentose within; petals white, elliptic, 8-10 mm. long; fruit short-oblong, rarely globose, about 10 mm. broad, 12-15 mm. long; drupelets large, 15-30; putamen reticulate, 3 mm. long.
Type locality: Railroad depot at Wells Beach, Maine.
Distribution: Open places, from Maine to Ontario and the Catskill Mountains; New York; apparently also in Wisconsin and Minnesota.

Rubus plicatifolius is a North American species of dewberry in the rose family. It is found in eastern and central Canada (Québec, Ontario, New Brunswick, Nova Scotia, and Newfoundland) and in the eastern and central United States (from Maine south to Virginia, west as far as Minnesota, Iowa, and Missouri).

Rubus plicatifolius is a prostrate shrub trailing along the surface of the ground, with straight (not curved) prickles. Leaves are compound with 5 egg-shaped leaflets, plaited and yellowish. Flowers are in elongated groups of several flowers. Fruits are cylindrical rather than spherical.

The genetics of Rubus is extremely complex, so that it is difficult to decide on which groups should be recognized as species. There are many rare species with limited ranges such as this. Further study is suggested to clarify the taxonomy.