Rubus pensilvanicus aka Pennsylvania Blackberry

Rubus pensilvanicus belongs to the rose family. Its common name is Pennsylvania blackberry. This shrub sheds its leaves each year. It grows in temperate parts of North America. NC State lists its native range as Canada and the central and eastern United States. It grows at woodland edges, along roads, and beside fences. It also grows in thickets and open woods. Other sites include savannas and meadows with weeds.

Its arching, woody canes can reach 10 feet [3 metres] tall. Cane tips take root where they touch the ground. This helps plants spread fast and form loose groups. Young canes are stout, with angled sides and pale green skin. With age, they turn red, reddish brown, or black. Strong, curved prickles line the sides of the canes. The green leaves are compound, with egg-shaped leaflets and toothed edges. Each leaf on a first-year cane has five leaflets. Those on second-year canes have three. The end leaflet has a clear stalk. Side leaflets have short stalks or none.

Second-year canes bear white flowers in short groups called corymbs. Each bloom spans about 0.08 feet [0.025 metres]. Blooms appear between April and June and last about three weeks. Leafy bracts can hide parts of the blooms. Bees, butterflies, and other insects visit the flowers. Black fruits follow from May to July. Each fruit has many small parts called drupelets. Each drupelet holds one seed. The juicy flesh tastes sweet and tart. At times, it leaves a bitter taste. People use the fruit for jam and jelly. Rain in early summer affects fruit size.

Grow this blackberry in full sun or part shade. It suits soil that drains well. The soil can stay moist or turn somewhat dry. Loam, clay-loam, and rocky soils suit it. NC State lists acid, neutral, and alkaline soils. Its listed hardiness range covers USDA zones 4 through 8. Canes that bear fruit die after their second year. Grow more plants by division or from stem cuttings. Its fast spread and prickles call for space and care.

This shrub suits gardens grown for food, woodland sites, and barriers. Its canes give wildlife cover all year. Songbirds and small mammals eat the fruit. So do foxes, raccoons, and bears. Birds and small mammals also eat seeds from rotted fruit. Deer and rabbits eat the leaves, though the shrub has some deer resistance. NC State lists two pests: raspberry cane borer and rednecked cane borer. It also lists Fusarium wilt of blackberry as a disease problem.