Developmental and Structural Section
Matthews, Merran L. , Endress, Peter K. .
Crossosomatales: floral structure and systematic relationships.
The order Crossosomatales (Crossosomataceae, Stachyuraceae, Staphyleaceae, Aphloiaceae, Geissolomataceae, Ixerbaceae, and Strasburgeriaceae) emerged only recently as a result of molecular systematic studies (Nandi et al. 1998, Savolainen et al. 2000, Soltis et al. 2000, Cameron 2003, Sosa & Chase 2003). However, its position within rosids is still unresolved. In traditional classifications the seven constituent families were far apart, and thus have never been comparatively studied before, and some are morphologically poorly known. A comparative study of the floral structure of Crossosomatales, including morphology, anatomy and histology, yielded new features of systematic interest and in general supports the molecular results. In particular the close relationship of Ixerbaceae and Strasburgeriaceae is supported, plus that of Ixerbaceae, Strasburgeriaceae and Geissolomataceae. Also supported is the relationship between Crossosomataceae and Aphloiaceae, which share a number of special traits, although they do not appear as a clade in molecular analyses. Potential floral synapomorphies for Crossosomatales or groups of families within Crossosomatales are pronounced pollen "buds", nectary recesses between androecium and gynoecium, postgenital union of free carpel tips, zig-zag micropyles, arils, T-shaped hairs, cell groups with clusters of yellow crystals, and cells with mucilaginous cell walls.
1 - University of Zürich, Institute of Systematic Botany, Zollikerstrasse 107, Zurich, Zurich, CH-8008, Switzerland
2 - University of Zurich, Institute of Systematic Botany, Zurich, CH-8008, Switzerland
Presentation Type: Paper
Location: Alpine A (Snowbird Center)
Date: Monday, August 2nd, 2004
Time: 10:15 AM