Pennsylvania blackberry

Description

Arching semi-deciduous shrub to 2 m high. Forms dense thickets. Primocane stems strongly angled with faces furrowed, with sparse non-glandular pilose hairs and few to many sessile dark red glands, prickles 2-6 mm long, mainly on angles. Flowering stems from the leaf axils of the floricane.Primocane leaves consisting of 5 leaflets; mature mid primocane leaflets with sparse pilose hairs below, mostly on veins, terminal leaflet usually largest, mostly 3-7 cm long and 1.5-4 cm wide, petiole 5-9.5 cm long. Floricane leaves at base of flowering stems consisting of 3 leaflets, lower surface of leaflets with sparse pilose hairs, terminal leaflet mostly 3-7.5 cm long and 1.5-4 cm wide, petiole 0.3-3 cm long.Inflorescence subcorymbose with 3-12 flowers. The first formed flowers usually solitary in the leaf axils of 3-leaflet leaves. Sepals with or without prickles. Petals 17-23 mm long, 10-15 mm wide, elliptic-obovate, white. Stamens longer than styles.Fruit ovoid to oblong, initially green, ripening red, maturing black.