This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Ascending, wand-like, entirely unarmed, or with a few weak prickles, glabrous or the younger shoots scurfy-pubescent, the stems 5°-12° long. Leaves long-petioled, pedately 5-foliolate, or some 3-folio-late; leaflets oval, thin, glabrous on both sides, long-acuminate or acute, rounded or narrowed at the base, often 6' long and 2' wide, sharply but not very deeply dentate; stalk of the terminal leaflet 1 1/2'-4' long; inflorescence loosely racemose; bracts linear-lanceolate; pedicels slender, ascending; sepals lanceolate, acuminate; fruit black, very pulpy, 8"-12" long.
Rubus hispidus var. suberecta Peck, Rep. N. Y. State Mus. 44: 31. 1891. Not R. suberectus Anders. 1815.
Rubus nigricans Rydb. in Britton, Man. 498. 1901.
Stems erect or ascending, 2°-4° high, the older parts densely clothed with slender stiff slightly reflexed bristles. Leaflets generally 5 in leaves of the sterile shoots, 3 in those of the flowering branches, obovate, mostly acute or short-acuminate, sometimes 4' long, short-stalked or sessile, green and glabrous on both sides; flowers 6"-9" broad, racemose; fruit small, sour.
In dry or marshy soil, Quebec and northern New York to Michigan and eastern Pennsylvania. Included in our first edition under Rubus set˛sus Bigel., which appears to be a hybrid between this species and R. hispidus L. July-Aug.
Rubus frondosus Bigel. Fl. Bost. Ed. 2, 199. 1824.
Rubus villosus frondosus Bigel.; Torr. Fl. U. S. I: 487. 1824.
Stems erect or arching, 2 1/2°-4° high, angled, bearing rather stout straight prickles, villous, especially when young. Leaves velvety-pubescent beneath, sparingly pubescent or glabrous above; leaflets elliptic to obovate, sharply serrate, acute or acuminate; racemes more or less elongated, the pedicels subtended by petioled, mostly uni-foliolate leaves (bracts); flowers about 1' broad; petals broadly obovate; fruit subglobose, black, falling away before the subtending leaves.
Mostly in dry soil, Massachusetts to New York, Ohio(?) and Virginia. May-June.