Abstract Detail



Anatomy and Morphology

Zhang, xin [1], zhang, zhixiang [2], zhao, zhong [1].

FLORAL ONTOGENY OF ILLICIUM LANCEOLATUM (SCHISANDRACEAE), WITH EMPHASIS ON CARPEL, OVULE AND FLORAL APEX DEVELOPMENT.

There are two competing hypotheses for the origin of flowers. The traditional hypothesis is phyllosporous origin which regards a conduplicate carpel as an ancestral form that is the result of longitudinally folded leaf-bearing ovules along its margins. Alternatively, the carpel formation is the result of a fusion between an ovule-bearing branch and its subtending leaf-like structure; if true, the ovule would appear in the middle of the leaf-like structure. For the majority of the angiosperms, the carpel is a single leaf-like structure with the ovule developing later on the lamina. Illicium, often included in Schisandraceae, is a member of the ANA grade that is known as one of the earliest diverging lineages among extant angiosperms. This genus with apocarpous gynoecium has various ancestral morphological characteristics in terms of the carpel, ovule, and floral apex. Although various aspects of Illicium morphology have been previously investigated, many evolutionary characteristics remain unclear. A more detailed examination of the carpel, ovule, and floral apex of Illicium is needed. In this study, the development of carpel, ovule, and the floral apex of I. lanceolatum was studied using LM and SEM. The results showed that the ovule primordium originates at the point where the carpel touches the floral axis. Based on the comparison with other taxa, the evolutionary implication of a persistent floral apex is an apical meristem remnant of a shoot. So the carpel of Illicium is a leaf-like structure that encircles the ovule. This kind of carpel fits the hypothesis that the carpel is a fusion of two parts, ovule-bearing branch, and its subtending leaf-like structure. 


1 - Norwest A&F University, Key Laboratory of Silviculture on the Loess Plateau State Forestry Administration, College of Forestry, Tai Cheng Road NO.3, Yangling, Shaanxi, 712100, China
2 - Beijing Forestry University, Lab of Systematic Evolution and Bio-geography of Woody Plants, College of Nature Conservation, No. 35 Qing Hua Dong Lu, Haidian Distrite, Beijing, 100083, China

Keywords:
angiosperms
flowers
carpel.

Presentation Type: Oral Paper
Number:
Abstract ID:718
Candidate for Awards:None


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