Abstract Detail



Anatomy and Morphology

Zumajo, Cecilia [1], Frangos, Samantha [2], Stevenson, Dennis [3].

Anatomical development of the ovules in Cycadales.

Cycadales are one of the most ancient lineages of extant seed plants, thus, it is one of the earliest lineages to have developed ovules as we know them today. Even though it is a lineage with a key phylogenetic position for the understanding of land plant evolution, and with an enormous diversity in megastrobili and ovule morphologies, detailed anatomical descriptions of the ovules are restricted to few species. Here we provide an anatomical examination of the ovules in 8 of the 10 different genera to identify features exclusive to each type of ovule. We also provide comparable stages throughout the integument development of Zamia furfuracea. We sectioned the ovules and subsequently stained them with Safranin and Alcian Blue.  Morphological observations were performed under the SEM. Additionally, ovules were cleared and stained with safranin or Schiff Reagent, in order to better observe and describe the vasculature. Anatomical features where identified that characterize ovules in cycadales. The sarcotesta has tannins, mucilaginous canals and vascular bundles whereas the sclerotesta and endotesta does not, except for Encephalartos where high accumulation of tannins was observed in the endotesta. By clearing the ovules, we were able to identify the two sets of vasculature in most of the species included in this study; the external system consists of several unbranched bundles in the  sarcotesta, and the internal system of profusely branched bundles that  enter and supply the nucellus. This comparative study was possible by compiling many years of preserved plant collections starting with those of C. J. Chamberlain and Knut Norstog.


1 - New York Botanical Garden, 2900 Southern Blvd. Bronx, New York, NY, 10458, United States
2 - New York Botanical Garden, 2900 Southern Blvd., Bronx, NY
3 - New York Botanical Garden, 2900 Southern Blvd., Bronx, NY, 10458

Keywords:
Developmental morphology
Cycadales
anatomy
Ovules
Evolution of development
Seed development.

Presentation Type: Oral Paper
Number: 0004
Abstract ID:263
Candidate for Awards:None


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