VON BALTHAZAR, MARIA* and PETER K. ENDRESS. Institute of Systematic Botany, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland. - Floral structure and phylogeny of Buxaceae.
Buxaceae is a small family of basal eudicots comprising up to five
genera (Buxus, Notobuxus, Pachysandra,
Sarcococca, Styloceras) and about 120 species. The
delimination of the family and the systematic relationships within the
family have been problematic in the past. Our previous molecular
study revealed two major clades: the clade of Buxus and
Notobuxus, and the clade of Pachysandra,
Styloceras, and Sarcococca.Pachysandra and
Styloceras form a strongly supported sister group to
Sarcococca. The African genus Notobuxus is embedded
among African members of Buxus. The basic structure of
inflorescences and flowers, in particular the development and trimery
of the gynoecium, of Notobuxus is very similar to that of
Buxus. The other major clade is also supported by identical
basic floral structures as the dimery of the gynoecium or the very
similar male flowers in Pachysandra and Sarcococca.
Floral structure and development of representatives of all genera have
been studied in detail and will be discussed in connection with the
molecular results.
Key words: basal eudicots, Buxaceae, floral development, floral structure, molecular phylogeny