全緣卷柏之葉舌

Ligule in Selaginella delicatula (Desv.) Alston

本文探討全緣卷柏（Selaginella delicatula (Desv.) Alston）葉舌之解剖和發生過程。葉舌之外形由單一指狀、至二、至多裂瓣狀之掌狀都有。組成葉舌之細胞明顯地可分為下列四組織區：舌鞘、舌足、基部和頸部。舌鞘由雙層之扁形細胞組成，舌足則為單層之細長且高度液胞化之細胞，一成長的葉舌之舌鞘及舌足細胞內皆具有內凸之胞壁，即為類似轉送細胞之構造。基部細胞之胞質濃、形等徑，而頸部之細胞則為長條形之細胞相互交錯而排。至後期，葉舌雖不脫落，但漸萎縮而老化。頸部最先是萎縮狀。本文並根據細胞形態推測葉舌內各組織區之可能功用。葉舌起源於二至三列之葉原原始表層之細胞，最早分化者為基部細胞，其次為舌足細胞， 再次為舌鞘細胞，最後為頸部細胞。

The anatomy and ontogeny of ligule in Selaginella delicatula (Desv.) Alston were examined using both optical and electron microscopes. The ligule varies in form, from finger-like, bi- to multilobed palmate, acropetally as four regions basing on the cell morphology. They are sheath, glossopodium, basal cell region and neck. The sheath cells as well as the glossopodial cells are transfer cell in the well developed ligule. The former is flattened double cell layered the latter is single row of elongated and highly vacuolated cells. Basal cell region is composed of relatively isodiametric protoplasmic cells whereas the cells in neck are overlapped each other in arrangement. The first indication of the senescence of a ligule is the shrinkage of neck cells. The possible function of each region of the ligule is assumed based on cellular structure. The ligule arises from two to three rows of adaxial protodermal cells at the junction of leaf primodium and stem. As it grows, the basal cells are the first tissue to be identified, followed by glossopodial cells, sheath cells and neck cells.