Abstract

The development of sporangium and sporogenesis in Isoetes taiwanensis DeVol are described. Based on cell lineage and cytoplasmic contents, the sporangium in I. taiwanensis is suggested to be of hypodermal origin. The ontogeny of microsporangium and megasporangium are the same in the early stage. The first indication of the young microsporangium is the differentiation of the irregular groups of deeply-staining cells (microsporocytes) and lightly-staining cells (which become trabecula, tapetum and part of sporangial wall), whereas the earlist indication as a megasporangium is the enlargement of the megasporocytes. The first fruiting leaves in the growing season are always megasporophylls, and then followed by microsporophylls. There is occasionally some irregularity in the order of succession, and sometimes a sporangium is found bearing both micro and megaspores.

中文摘要

此篇是描述臺灣水韮 (Isoetes taiwanensis DeVol)的孢子囊發育和孢子生成過程。根據細胞的排列及細胞質形態，可以認為台灣水韮 (I. taiwanensis) 是起源自皮下組織(Hypodermal origin)。小孢子囊和大孢子囊的早期發育很相似，形態上無任何差別，直到小包子囊內部組織分化為不規則深染色區 (即小孢子母細胞) 及淺染色區 (不孕性細胞區，如trabecula、營養層和孢子囊壁）而可辨別，此期在整個小孢子囊內之各種細胞之大小甚為一致。但在大孢子囊內大孢子母細胞不斷增大至比鄰近細胞約四至五倍大，才可做辨別大孢子囊的指標。在一生長季中，其先形成的孢子葉，通常是大孢子葉，隨後才有小孢子葉，其消長次序並不太規則，有時在同一孢子囊內同時具有大孢子和小孢子，但為數甚少，約佔1.9%。