Abstract

The development of the female gametophyte in Isoetes taiwanensis DeVol is described. In the early stage of endosporic gametophyte development, the primary nucleus moves from base to apex and undergoes repeated nuclear division to form a free nuclear structure in the apical region. When there are only a few nuclei, the wall formation proceeds around the nuclei both basipetally and centripetally. Karyogenesis and cell wall formation could occur at the same time resulted in binucleate or multinucleate cells. In the full cellular stage, the relatively sharp border between the upper small celled and lower large celled area can be recognized. The lower large cells are rich in food particles. The first archegonial initial arises from a single superficial cell beneath the tri-ridge of the spore wall. The number of archegonia formed in each gametophyte is not constant ranging from 5 to 20. Rhizoids originated also from the superficial cells of the apical region are always on the exposed area after the spore wall breaks. The outgrowth of gametophytic tissue from megaspore wall mainly takes place in December to February indicating it might need cooler weather.

中文摘要

本篇描述台灣水韮(Isoetes taiwanensis DeVol)的雌性配子體發育和藏卵器生成過程。在早期發育，成熟孢子的核由基部移到上端，並在上端進行多次核分裂。只分裂至十數個核時，其核四周開始細胞壁之形成，細胞壁形成次序是由上而下，由四周向中心。隨同細胞壁形成，這些核仍不斷進行核分裂。所以，在發育完全的配子體，仍可看到多核現象。在一發育完全的配子體中，其上部細胞較小，而底部細胞較大，二者的差別非常顯著。其底部較大的細胞通常富含澱粉、蛋白質、油脂之類物質。藏卵器通常位於孢子壁開裂口下，起源自早期形成的頂部表面細胞，每一配子體生成藏卵器的數目不定，約5~20個左右，假根也來自配子體的表面細胞，通常在孢子壁開裂後露出的配子體部分生成，常可達1公分左右。配子體由孢子壁向外生長時期，大多在十二月至次年二月，顯示配子體的成熟需要較低溫度。