BROUILLET, LUC. Herbier Marie-Victorin, IRBV, Universite de Montreal, 4101 Sherbrooke St. E., Montreal, QC, Canada, H1X 2B2. - Begoniaceae and the Cucurbitales: A morphological phylogenetic analysis.
In the last 20 years, the relationships of the Begoniaceae have been
redefined. Molecular phylogenies have shown that the family, along
with its traditional allies Datiscaceae and Tetramelaceae, belongs to
the Curcubitales, with the Cucurbitaceae, a relationships already
foreseen, but also with Corynocarpaceae, Coriariaceae and
Anisophylleaceae, relationships that had never been predicted on the
basis of non-molecular data. To illustrate potential evolutionary
trends in the order, significant morpho-anatomical characters are
mapped onto the rbcL and 18S molecular trees. An independant
phylogenetic analysis of morphological data is also presented, as well
as a combined analysis of morphological and molecular data. Features
of the order that attract attention include the plagiotropic
architectural habit associated with spiro-distichous leaf disposition
(to distichous-opposite), and the possibility that the primitive state
for the ovary may have been inferior, evolving into superior ovaries
in Coriariaceae-Corynocarpaceae. Gaps in our knowledge of the group,
and the significance of this analysis in terms of Begoniaceae
morphology are discussed. Biogeographic ramifications will also be
considered.
Key words: Begoniaceae, biogeography, character evolution, Cucurbitales, morphological phylogeny