Northern Ontario Plant Database
Rubus allegheniensis Porter
En: Alleghaney blackberry, common blackberry, sow-teat blackberry
Rosaceae (Rose Family)
General: A deciduous shrub, 1-3 m tall, with biennial, erect to arching, 5-ridged or angular, reddish-purple stems (canes), often forming dense thickets. Young and mature canes are usually armed with scattered broad-based prickles, 3-10 mm long, and stalked glandular 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 hairy (pubescent) and bear stalked glands as well as small recurved prickles. The terminal leaflet is ovate, 6-20 cm long and 3-11 cm wide, and stalked, the petiolule 1.5-5 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 nearly sessile, with petiolules <1-4 mm long. All leaflets are green above with scattered hairs, green and velvety-pubescent beneath; margins are sharply toothed (serrate), often double-toothed (double-serrate).
Flowers: Bisexual, arranged in terminal clusters (racemes), 1-3 dm long, of up to 20 flowers. The floral axis (rachis), flower stalks (pedicels), and calyx lobes are densely glandular-pubescent with stalked glands and slender, straight to slightly curved prickles. Calyx green, with 5 ovate, acuminate lobes; petals 5, white, oblanceolate to obovate, 10-20 mm long, 4-12 mm wide; stamens numerous, spreading; pistils numerous, superior; the styles persistent in fruit. Flowers bloom in early to mid summer.
Fruit: A rounded, aggregate fruit, to 2 cm long, composed of a cluster of small drupes (an aggregate of drupelets), becoming purplish-black when mature; edible and juicy or dryish; not separating from the receptacle. Fruits mature in late summer.
Habitat and Range: Thickets, forest edges, and open and disturbed habitats, such as abandoned fields, rights-of-way, and roadsides. The common blackberry has an eastern North American range and occurs throughout southern and eastern Ontario, extending northwest to the Wawa area.
Similar Species: The smooth blackberry (Rubus canadensis
Blackberry canes are similar in appearance to those of raspberries (Rubus idaeus