• (a.) At the same node with opposite or whorled leaves, but occupying a position between their places of attachment.
In`ter·fo`li·a'ceous adjective [ Prefix inter- + foliaceous : confer French interfoliacé .] (Botany) At the same node with opposite or whorled leaves, but occupying a position between their places of attachment. 
Between the leaves, particularly between two leaves of a pair.
situated between leaves, esp. opposite leaves.