Blackberry and grape can spread as a dense thicket or climb as a vine over fallen debris and up trees and shrubs. Both species frequently climb over elderberry shrubs, and though elderberry is not extremely shade tolerant, its multiple stems can reach through the vines to receive enough sun.
(Above) Elderberry shrub with blackberry vine.
The multiple vines and stems form thick cover that is often extensive across the forest floor. Wildlife can use this as cover for foraging or dispersing, and the stems at multiple heights create a variety of locations for nests.