Common blackberry is an erect shrub, the branches occasionally to 8 feet and arching high or being supported by surrounding trees or shrubs.
Leaves are alternate, compound, with 3–5 leaflets; leaflets 2½–4 inches long, egg-shaped, edges coarsely toothed; medium green above, paler below. The end leaflet on primary canes are 3¼–5 inches long, or 2–3 times longer than broad.
Stems consist of canes with broad-based, recurved thorns. The primary (first-year) canes are green to reddish, ribbed, with numerous prickles. Flower canes (second year) are brown.
Flowers April–June, in clusters 4–5 inches long, or 2–4 times as long as broad, rather elongated and cylindrical. Flowers 6–12 and sometimes to 30, showy, ¾ inch across, petals 5, white oval; stamens numerous.
Fruits June–August. Abundant, deep violet to black, glossy juicy, sweet, globe-shaped or cylindrical, about ¾ inch long.
Similar species: Rubus is a large genus with nearly 30 species recorded in Missouri. Included in the genus are blackberries, raspberries, loganberries, dewberries, and brambles. The members of genus Rubus often interbreed and hybridize, and the canes often change their appearance between first and second growing seasons, making them a tricky group even for botanists to sort out. The genus has been divided into 6 subgenera and sections in our state.