Abstract

Seed morphometry and Scanning Electron Microscopic studies on 10 species of epiphytic orchids from Western ghats of Karnataka are presented. All the presently investigated taxa are different in their seed surface characters including size, shape, visibility of embryo, testa cells and structure, curvature and ridges. Seed colours range from pale yellow to yellow, brown and white. Variation between maximum and minimum in the length/width ratio of seed is discussed. Data on the seed volume show that higher seed volume is the result of both greater length and width. Maximum width of testa cell and seed volume are found in Cymbidium bicolor. Variations in seed and embryo volume and percent air space could exist among the different taxa of orchids. The volume of the embryo changes during its developments from zygote to seedling. Increase in the percentage of air space is due to increase in the cell length of the testa. Seeds with higher percentage of air space get dispersed over wide geographical areas.

中文摘要

本文利用掃描電子顯微鏡觀察印度Karnataka 西部山區10 種附生蘭種子之形態並加 以測量。這些種均具有不同的種子表面特性，包括種子大小、形態、胚的活力、種皮構造、彎曲度與稜線等等。種子顏色從淡黃到黃色、棕色與白色都有。種子的長寬比之大小變異亦加以討論。種子的體積乃是由種子的長與寬所決定。Cymbidium bicolor 有最大的種皮細胞寬度與種子體積。不同種類之間的種子與胚之體積與空氣所佔有的百分比都有一些變異。氣室比例之所以增加乃是因為種皮之細胞長度增加，種皮氣室所占比例高者有助於種子之散佈。

Keyword: Air space, Cymbidium bicolor, Scanning Electron Microscope, Orchids, Seed Morphometry