hamamelidae

n. a group of chiefly woody plants considered among the most primitive of angiosperms; they have a perianth poorly developed or lacking, and flowers often unisexual and often in catkins and often wind pollinated. The group contains 23 families including the Betulaceae and Fagaceae (includes the Amentiferae); sometimes it is classified as a superorder.
Syn. -- subclass Hamamelidae. [ WordNet 1.5 ]