Morphology of gametophytes and young sporophytes of Sphaeropteris lepifera

Sphaeropteris lepifera is one of the largest tree ferns in Taiwan. On avera ge, it produces 50.7 sporangia per sorus, and 64 spores per sporangium. Spo re germination, after 2 years of storage at 4 degreesC was over 95%. The pa ttern of spore germination was "Cyathea-type", and the gametophytes exhibit ed mainly Drynaria-type development with occasional Adiantum-type developme nt. Typical gametophytes were heart-shaped but had the potential to elongat e and become elliptical. Multicellular hairs on the dorsal and ventral surf aces of the midrib cushion increased in size and changed shape with age. Th ey were usually uniseriate when young, and became multiseriate with age. Ga metophytes initiated antheridia about 1 month after spores were sown, and d id not become hermaphrodites until 7 weeks later. During ontogeny, the game tangial sequence was from the male to hermaphroditic. Antheridia formed on the wings of the ventral and dorsal surfaces of gametophytes. The wall of e ach antheridium was composed of 5 cells. Archegonia appeared on the cushion of the ventral surface of gametophytes. Some gametophytes initiated clone- formation through vegetative regeneration. When sufficient water was provid ed, young sporophytes began to appear 12 weeks after spores were sown. The first fronds were midribless. The uniseriate, multicellular hairs on young sporophytes were similar to those on gametophytes.