Developmental and Structural Section
Bachelier, Julien B. , Endress, Peter K. .
Floral structure of Kirkia wilmsii: implications for the systematic relationship of Kirkiaceae and the Anacardiaceae-Burseraceae clade (Sapindales).
Kirkiaceae were formerly a subfamily (Kirkioideae) placed in Simaroubaceae (Sapindales) but molecular phylogenetic studies repeatedly suggested that they could be sister to the clade of Anacardiaceae plus Burseraceae. Although the systematic position of Kirkioideae in Simaroubaceae was never strongly supported, no other affinity within Sapindales has been discussed except for the first description of Kirkia in which a resemblance with the fruit of Boswellia (Burseraceae) was suggested.
Floral structure and development of Kirkia wilmsii were studied in detail.
The tetramerous, isomerous and haplostemonous flowers of Kirkiaceae are morphologically bisexual but functionally unisexual. The gynoecium is syncarpous and entirely synascidiate in the ovary. It is apocarpous further up. However, the free tips of the carpels are postgenitally united and form a stigmatic head with a compitum. The former center of the floral apex is not included in the ovary but positioned on the unusual central protrusion on top of the ovary. Each carpel is uniovulate and ovules are crassinucellar, bitegmic, and anatropous-antitropous.
Most of the floral features of interest in Kirkiaceae are not unique to the family and are more or less widespread in other sapindalean families and malvid groups. Similarities are especially obvious with Burseraceae and Spondioideae (Anacardiaceae). The systematic position of Kirkiaceae as sister to Anacardiacae plus Burseraceae may help to understand the different trends of gynoecium evolution in the clade of Anacardiaceae plus Burseraceae.
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1 - University of Zurich, Institute of Systematic Botany, Zollikerstrasse 107, Zurich, 8008, Switzerland
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, July 29th, 2008
Time: 9:00 AM