Northern Ontario Plant Database
Rubus canadensis L.
En: Canada blackberry, smooth blackberry
Rosaceae (Rose Family)
General: A deciduous shrub, 0.5-3 m tall, with biennial, erect to arching, reddish-purple to brown stems (canes), usually 5-ridged or angular in cross section; often forming dense thickets. Young canes and leaf stalks (petioles) are smooth (glabrous) to slightly hairy (pubescent); stout broad-based prickle are lacking, but scattered slender prickles may be present; new stem and leaf growth often bears glands (sessile to short-stalked) and scattered hairs.
Leaves: Alternate, palmately compound, and stalked (petiolate). Vegetative canes (primocanes) have leaves with 5 leaflets; those of the second-year flowering canes (floricanes) have 3 leaflets or a reduced, simple, lanceolate leaf. Petioles are usually smooth (glabrous) or bear 1-2 scattered slender prickles. The terminal leaflet is ovate, 9-20 cm long and 4-5.5 cm wide and stalked, the petiolule 3-10 cm long; the base is rounded to cordate; the apex is long and narrowly pointed (attenuate to caudate). Lateral leaflets are lanceolate to ovate and smaller than the terminal leaflet; the middle pair of leaflets has shorter petiolules, while the lowest pair of leaflets is sessile or nearly so, with very short petiolules, <1-5 mm long. Leaflets are green and essentially glabrous on both surfaces; although a few scattered hairs may be present, especially on veins, the lower surface does not feel velvety; margins are sharply toothed (serrate) to often double-toothed (double-serrate). Leaves of the floricanes are smaller and have oblanceolate to obovate leaflets with tapering (cuneate) bases and pointed (acute or short-acuminate) apices.
Flowers: Bisexual, arranged in elongate clusters (racemes) of up to 25 flowers at the end of erect to ascending floricanes. Flowers are subtended by reduced, leaf-like bracts (foliaceous bracts). The floral axis (rachis) and pedicels are minutely hairy (pilose); pedicels are 2-4 cm long. The calyx is green, with 5 ovate lobes, to 7 mm long, acuminate to caudate-tipped; the outer surface of the calyx is slightly pubescent to glabrous; the inner surface is densely white woolly-pubescent; petals 5, white, oblanceolate to obovate, 11-20 mm long, 6-12 mm wide; stamens numerous, spreading; pistils numerous, superior; the styles persistent in fruit. Flowers bloom in early to mid summer.
Fruit: A rounded to ovoid, aggregate fruit, composed of a cluster of small drupes, (an aggregate of drupelets), becoming purplish-black when mature; to 1.2 cm long, often dryish, occasionally juicy; the fruit remains firmly attached to the receptacle. Fruits mature in late summer.
Habitat and Range: Thickets, forest edges and clearings, and open and disturbed habitats, such as abandoned fields, rights-of-way, and roadsides. The smooth blackberry has a northeastern North American range, and occurs throughout southern and eastern Ontario, extending northwest to the Wawa area, with a disjunct population at the lower end of Lake Nipigon (Soper & Heimburger 1982).
Similar Species: The common blackberry (Rubus allegheniensis
Blackberry canes are similar in appearance to those of raspberries (Rubus idaeus