Study on structure and life cycle of Asplenium nidus L.

Study on structure and life cycle of Asplenium nidus L. was undertaken at the Department of Botany, during November 1997 to November 1998. The proposes of this study were for preserving the endangered fern and promoting the decorative plant business. The results showed that its life cycle was composed of two alternating generation, a haploid (n) phase, known as the gametophytic generation and a diploid (2n) phase, known as the sporophytic generation. The sporophyte was formed and alttached on the gametophyte for a period of 3 months. Thereafter, this sporophyte would separate and continue growing as a free living fern. The sporophyte of this fern produced the bean-shaped of homospore in the oval sporangium formed beneath of their fronds (abaxial). At maturity, the spores were forcibly discharged from the sporangium by contraction of annulus cells. The morphological stages and the periods of gametophyte development were investigated by culture of spores on the Miller and Miller medium. These stages were 1) filament of cells as protonema 2) heart shape of gametophyte (prothallium) and 3) mature gametophyte, in the period of 1, 4 and 6 months after culture, respectively. On the mature gametophyte, male (antheridium) and female (archegonium) reproductive were found. Antheridia were formed throughout the gametophyte (prothallium) and were clustered at rhizoid region whereas archegonia were found only on apical notch. Some cells within the antheridia differentiated to be sperm whereas a single cell developed to an egg within archegonium. Zygote was formed by the fusion of sperm and egg, thereafter developed through embryo and young sporophyte, consequently. The period of young sporophyte development of this fern was about 9 months under culture conditions. Further comparative study revealed that the using of rough choped Platycerium holttumii Jonch. & Hennipm. As planting media for propagation was better than using soil media indicating by their growth.