Root graft

A root graft is when roots from one plant meet with the roots of another plant to form a mutually beneficial network to share nutrients, water, and hormones. More than 160 tree species can form root grafts with other trees in the same species, of which approximately 30 of these species can form root grafts with other species in the same genus, such as white birch with yellow birch. Some root grafts can even occur over different genera, such as between birch and maple or birch and elm.

These grafts help synchronize a tree's flowering time to help ensure cross-pollination.