2. Rubus occidentalis L. (black raspberry)
Pl. 542 j, k;
Map 2500
Canes to 400 cm
long, erect, to 200 cm tall when young, but ultimately arching and often
rooting at the tips. Primocanes bluish green in summer, turning purple (or
rarely yellowish green) in winter, often glaucous, 3–6 mm in diameter. Prickles
sparse to moderate, 0.2–1.7 prickles per cm of cane, broad-based and
downward-curved, 3–5 mm long. Petioles armed with broad-based, downward-curved
prickles 1–2 mm long. Stipules 4–8 mm long, threadlike. Primocane leaves
palmately compound with 3(5) leaflets, the margins coarsely and doubly toothed,
the upper surface glabrous to thinly hairy, the undersurface white-felted.
Central primocane leaflets 7–12 cm long, 4–9 cm wide, ovate to elliptic,
cordate to rounded at the base, angled or tapered to a sharply pointed tip, the
leaflet stalk about 1/4–1/2 as long as the leaflet blade; lateral leaflets
ovate to ovate-elliptic, rounded to broadly angled at the base, tapered to a
sharply pointed tip, the middle pair (when present) stalked, the basal pair
nearly sessile, occasionally with asymmetric basal lobes. Inflorescences simple
to complex clusters, in extreme cases paniculate, 8–40 cm long, with
(3–)5–19(–27) flowers and (3–)5–13 leafy bracts, these nearly all with 3 leaflets;
flower and inflorescence stalks with fine hairs, needlelike prickles (that at
10× magnification seem to be made of ivory), and occasional small, broad-based
prickles, the flower stalks branched on the most vigorous inflorescences.
Sepals 5–9 mm long, 2–3 mm wide, triangular-ovate to triangular-elliptic.
Petals 2–5 mm long, narrowly obovate, white. Fruits 12–15 mm long, 12–15 mm
wide, hemispheric, purplish black (rarely amber) when ripe. 2n=14.
April–June.
Scattered nearly
throughout the state (northeastern U.S. and adjacent Canada south to South
Carolina, Georgia, and Arkansas and west to Oklahoma, Nebraska, and North
Dakota). Mesic upland forests, bottomland forests, bases and ledges of bluffs,
banks of streams, upland prairies, loess hill prairies, and savannas; also
pastures, fencerows, ditches, railroads, and roadsides.