Developmental and Structural Section
Campbell, Lisa M. , Stevenson, Dennis Wm. .
Anatomy and Development of Gynoecium Appendages in Xyridace.
As currently understood, the commelinoid family Xyridaceae are a morphologically diverse assemblage that includes about 385 species in five genera. The family is characterized by a three-merous flower with a differentiated perianth and a petaloid corolla. Amongst the genera, variation occurs in all whorls of the flowers, including persistence and morphology of the median sepal, fusion in the corolla, presence and form of antesepalous staminodia, staminal attachment, branching of the style, and the presence of appendages on the tricarpellate gynoecium. Gynoecium appendages occur in the three genera that have been recognized as the subfamily Abolbodoideae. Aratitiyopeaand Orectanthe have similar appendages that are large, monomorphic, and located on top of the ovary. In Abolboda, the appendages are delicate structures of unequal size that occur on the style. In all genera, the appendages are vascularized, the epidermis lacks stomata, and in the distal region the epidermal cells are papaillate. The appendages are initiated on the dorsal side of each carpel. The carpel dorsal vascular bundle eventually bifurcates with one branch entering an appendage and the other entering the style. Gynoecium appendages in the dorsal position also occur in some Eriocaulaceae, and are reported to be nectar-secreting. Stützel (1990) determined that they share with Xyridaceae a similar early ontogeny. Although the appendages of Xyridaceae appear to be secretory, nectar is not known in the family, and the precise physiologic function of these structures is unclear.
1 - New York Botanical Garden, Bronx, New York, 10458, USA
Presentation Type: Paper
Location: Alpine A (Snowbird Center)
Date: Wednesday, August 4th, 2004
Time: 2:00 PM