Systematics Section / ASPT
Mohammad, Inamuddin , Faris, Najat. M .
A contribution to the comparative morphological, embryological and anatomical studies of Urginea martima (L.) Baker and Scilla autumnalis L.
Urginea maritima(L.) Baker and Scilla autumnalis L. are characterized by the presence of well-developed tunicate bulbs and anthesis before leaves formation. The development of anther wall is of Monocotyledonuos type. The one layered middle layer is ephemeral.The endothecium in U.maritima is 1-layered.1-3 layers endothecium formation is of common occurance in S.autusmnalis.Fibrous thickenings differentiate on both sides of the anther wall.The microspore mother cells undergo meiotic divisions successively to give rise to isobilater microspore tetrads.Rarely,tetrahedral, linear,T-shaped and rhomboidal microspore tetrads have also been observed in U.maritima. Sometimes, phenomenon of cytomixix occurs in S.autumnalis.The mature pollen grains are shed at 2-celled stage.The ovules are anatropous, bitegmic and crassinucellate.The funicular obturator and hypostase are well-developed. The hypodermal archesporial cell directly functions as megaspore mother cell. The megaspore mother cell undergoes reduction divisions and gives rise to a linear megaspore tetrad. Rarely,T-shaped megaspore tetrads may occur in U.maritima.The chalazal megaspore becomes functional and develops into Polygonum type of embryosac. The polar nuclei fuse to form secondary nucleus prior to the entry of pollen tube.Stigma is receptive and glandular.The development of endosperm is Helobial type. The seeds setting are common in both the taxa.The thickly lignified inner epidermis of the ovary wall in U.maritima coils up which could help in the dehiscence of the fruit. The vascular bundles are arranged in two rows in the leaf of U.maritima while it is only in one row in S.autumnalis.Similarly the xylem in U.maritima are arranged in two separate rows whereas in S.autumnalis they are in one row. Moreover the xylem is Y-shaped in S.autumnalis. The external morphological,embryological and anatomical characters have been compared between U.maritima and S.autumnalis and it is concluded that S.autumnalis should be retained in the same genus as reported earlier rather than to shift it to the genus Urginea.
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1 - University of Guyana, Biology, Faculty of Natural Sciences, Turkeyen Campus, Georgetown, Guyana, South America
2 - Al-Fateh University, Botany, Tripoli, Libya
Presentation Type: Oral Paper:Papers for Sections
Location: Continental A/Hilton
Date: Tuesday, July 10th, 2007
Time: 10:30 AM