Smilacaceae
Smilacaceae, the greenbrier family, is a family of flowering plants. Up to some decades ago the genera now included in family Smilacaceae were often assigned to a more broadly defined family Liliaceae, but for the past twenty to thirty years most botanists have accepted Smilacaceae as a distinct family. It is considered that the two families evolved around 55 millions years ago during the Early Paleogene possibly near the boundary between Paleocene and Eocene. One characteristic that distinguishes Smilacaceae from most of the other members of the Liliaceae-like Liliales is that it has true vessels in its conducting tissue. Another is that the veins of the leaves, between major veins, are reticulate (net-shaped), rather than parallel as in most monocots.
Classification
The APG II system, of 2003 (unchanged from the APG system, of 1998), recognizes this family and places it in the order Liliales, in the clade monocots. Within APG II it is a family of probably two genera Heterosmilax and the larger Smilax. However more recently Heterosmilax has been found to have arisen from within the ranks for Smilax.