Wikipedia
Hamamelididae is an obsolete botanical name at the rank of subclass. Because some hamamelidid members are bearing aments (i.e., catkins), this suclass has been formerly known as Amentiferae. Based on molecular phylogeny works, Hamamelididae appears to be a polyphyletic group.
A well-known system that used the name Hamamelididae is the Cronquist system, although in the disallowed spelling Hamamelidae. In the original 1981 version of this system the circumscription was:
- subclass Hamamelidae order Trochodendrales order Hamamelidales order Daphniphyllales order Didymelales order Eucommiales order Urticales order Leitneriales order Juglandales order Myricales order Fagales order Casuarinales
As is true for any botanical name, circumscription of the subclass will vary with the taxonomic system being used; the only requirement being that it includes the family Hamamelidaceae. The APG II system does not recognize named taxa above the rank of order but places most of the taxa involved in the rosids clade, with Hamamelidaceae itself in order Saxifragales.