- Identify blackberry patches by looking for thorny dense shrubs that form impassable thickets in the wild. The shrubs commonly grow up to 13 feet tall. Blackberry plants are ramblers rather than climbers.
- Look for canes that arch over outside of the patch. Blackberry plants spread aggressively by sending up long canes. As the canes mature, they lie down on the ground outside of the patch. Where the cane touches the soil, new roots grow, creating a new plant. Depending on the species, blackberry canes can grow up to 40 feet long.
- Examine the flowers closely. Blackberry flowers are white with five petals. In spring through summer, blackberry patches have white flowers that appear toward the tips of the canes.
- Identify the leaves by looking for dark green colored leaves with white fuzz on the surface. The leaves are made up of three to five leaflets forming around a center ridge. Turn over the leaf. Blackberries have a row of thorns on the ridge in the center of the leaflets.
- Identify the fruit. Blackberries are an aggregate fruit, a fleshy berry made up of multiple drupes. As the berries ripen, they turn from white to red and deep purple and black when fully ripe.
- Pick the fruit. The biggest difference between a raspberry and a blackberry is how the fruit comes off the vine. Raspberries leave the core behind and are hollow when picked. Blackberries keep the core and have a white center at the top of the fruit.