Rather soft-wooded usually deciduous shrubs, mostly armed with prickles, erect,trailing, or scrambling over supports. Shoots moderate, often angled, pith relatively large, round or angled, continuous. Buds moderate, sessile, oblong-ovoid. Leaf-scars like Crataegus, this is a most difficult group taxonomically. It is believed that the few, ancient, stable species inhabiting eastern North America at the time of its settlement have given rise through crossing to numerous incipient "species", some fertile and some apomictic, many of which are spreading rapidly. An astonishing number of such "species" seem to appear in certain small areas, for example, in New England, and in the Alleghenies of West Virginia. It is impossible to describe a genus such as this except in a tentative manner, and it will be recognized that identification in winter is virtually impossible. Except for a few clear-cut species of raspberries, the following key is designed to separate the larger groups (subgenera, or sections) only.
* Based on data furnished by H. A. Davis alternate, torn and irregularly shriveled on the persistent base of the petiole; bundle-trace not discernible; stipules often persistent at the top of the petiole remnant.
Fig. 143. Rubus odoratus.
Fig. 144. Rubus phoenicolasius.
Fig. 145. Rubus strigosus.
Plant habitually unarmed
Plants habitually armed, but with thornless or nearly thorn-less mutations
b. Canes upright
c. Canes habitually weakly armed (Raspberries)
d. Plant red-hairy all over
d. Plants not red-hairy
e. Stems bristly, not glaucous
e. Stems prickly, very glaucous
c. Canes habitually strongly armed (sometimes nearly thornless) d. Canes hispid or setose, prickles few (Bristleberries: R. setosus Bigel., etc.) d. Canes not hispid or setose, prickles usually numerous (Blackberries) e. Canes nearly without prickles or with only a few straight ones (Smooth Blackberries; R. canadensis L., etc.) e. Prickles abundant, hooked or bent or at least broad-based f. Panicle-vestiges glandular (Copsy Highbush Blackberries: R. allegheniensis Porter, Fig. 148, etc.) ' f. Panicle-vestiges not glandular (Field Highbush Blackberries: R. argutus Link, etc.) b. Canes trailing on the ground c. Canes hispid or bristly (Groundberries: R. hispidus L., Fig. 148, etc.) c. Canes prickly rather than exclusively bristly (Dewberries: R. flagellaris Willd., etc.)
1. R. odoratus L. Purple Flowering Raspberry. Stems shrubby, unarmed but more or less bristly, 1-2 m.high; bark shredding. Rocky places, Quebec and Ontario, south in the mountains to Georgia and Tennessee (Fig. 143).
2. R. phoenicolasius Maxim. Wineberry. Stems biennial, long and curving, rooting at the tips, beset with long red-brown glandular hairs and weak, nearly straight prickles. Introduced from Asia, originally cultivated, now extensively naturalized (Fig. 144).
3. R. strigosus Michx. Wild Red Raspberry. (R. idaeus L. var. strigosus (Michx.) Maxim.). Stems shrubby, 1-2 m. high, densely clothed with weak glandular bristles, or the older stems with small hooked prickles. Thickets, Labrador to British Columbia, south to West Virginia, Wisconsin, Nebraska, and Wyoming (Fig. 145).
4. R. occidentalis L. Black Raspberry. Blackcaps. Stems very glaucous, recurved, often rooting at the tip, sometimes 3-4 m. long, sparingly armed with small hooked prickles. Rich thickets, Quebec to Minnesota, south to Georgia and Colorado (Fig. 146).
Fig. 146. Rubus occidentalis.
Fig. 147. Rubus hispidus.
Fig. 148. Rubus allegheniensis.