THE ULMACEAE, ONE FAMILY OR 2 - EVIDENCE FROM CHLOROPLAST DNA RESTRICTION SITE MAPPING

The Ulmaceae is usually split into two subgroups, referred to as eithe r tribes or more commonly subfamilies (Ulmoideae and Celtidoideae). Th e two groups are separated, with some exceptions, on the basis of leaf venation, fruit type, seed morphology, wood anatomy, palynology, chem istry, and chromosome number. Propositions to separate the two groups as distinct families have never gained general acceptance. Recent morp hological and anatomical data have suggested, however, that not only i s family status warranted but that Celtidaceae are more closely relate d to Moraceae and other Urticales than to Ulmaceae. In order to test t hese alternative sets of relationships, restriction site mapping of th e entire cpDNA was done with nine rare cutting enzymes using 11 genera of Ulmaceae s. 1., three other families of the Urticales, and an outg roup family from the Hamamelidae. Cladistic analysis of the data indic ates that Ulmaceae s. 1. is not monophyletic and that distinct familie s (Ulmaceae and Celtidaceae) are warranted; that Ulmaceae is the siste r group to Celtidaceae plus all other families in the order; and that Cannabaceae might be nested within Celtidaceae. Familial placements of various problematic genera (e.g. Ampelocera, Aphananthe) are resolved and character evolution of key morphological, anatomical, chemical, a nd chromosomal features are discussed.