In this leaf arrangement pattern, leaves alternate on either side of the stem; just one simple or compound leaf is attached to each node.
Image Above: Alternate leaf arrangement of Texas sugarberry trees (Celtis laevigata).
Definition adapted from URL: http://en.wikipedia.org/wiki/Leaf#Arrangement_on_the_stem
Image from URL: http://www.bio.txstate.edu/~dlemke/