Abstract Detail

Celebrating More Than Three Decades of Research in Nymphaeales: A Colloquium Honoring Ed Schneider

Endress, Peter K. [1].

Ancestral traits and specializations in the flowers of the basal grade of living angiosperms.

Carpel structure in the ANITA grade (Amborella, Nymphaeales, Austrobaileyales, and potentially also including Chloranthaceae and Ceratophyllaceae) is largely ascidiate and sealing is by secretion, and not by postgenital fusion. Although the shape of the resulting slit of closure is intimately connected with the ascidiate or plicate shape of the carpels, ascidiate carpels can close in different ways. The most common types in the ANITA grade are a simple transverse slit or a short median longitudinal slit in the upper part of a carpel. A style is almost always absent. In the rare cases of a style-like apical extension, the extension is flat (Hedyosmum) or rounded and unifacial (Ceratophyllum), or, if it is closed forming a tube, it is not folded but is just the tubular elongated upper ascidiate zone (Cabombaceae, Austrobaileyaceae, Schisandraceae, except Illicium). A simple transverse ventral slit is especially characteristic for the ANITA grade, notably including Chloranthaceae and Ceratophyllaceae. It is formed when the carpel has a single median ovule and a (plicate) style is absent. A short longitudinal slit occurs in carpels with several ovules. - Some other ancestral features will also be addressed.
Specializations in Amborella are the functionally (but not morphologically) unisexual flowers and the shallow floral cup, which perhaps evolved together with a moderate increase of floral parts, especially stamens. This cup forms a plate-shaped floral base on which the stamens are presented in the male flowers. Most conspicuous is the gigantism in the flowers of some Namphaeaceae, increase in organ number, partial syncarpy, and pollination by large beetles - probably a relatively recent specialization. But in contrast, the dwarfism and reduction of the flowers with unique stigmatic hairs in Hydatellaceae is also remarkable. In Chloranthaceae and Ceratophyllaceae, flowers are reduced to a single stamen or a single carpel and are unisexual in Hedyosmum and Ascarina. In Chloranthus, the broad, uniquely three-lobed stamen serves as a protective scale for the gynoecium during development and later also for pollinating thrips. The puzzling "window frames" in female Hedyosmum flowers and also floral bracts differentiate as aril-like structures in fruit.

1 - University Of Zurich, Bot Garten & Inst Fur Sys Bot, Zollikerstrasse 107, Zurich, CH-8008, Switzerland

Keywords:
ANITA grade
Amborella
Nymphaeales
Austrobaileyales
Chloranthaceae
Ceratophyllaceae
flowers
carpels
stamens
ancestral traits
specializations.

Presentation Type: Colloquium Presentations
Session: C3
Location: Salon 12/The Shaw Conference Centre
Date: Tuesday, July 28th, 2015
Time: 9:45 AM
Number: C3005
Abstract ID:180
Candidate for Awards:None