Morphology of the Gametophytes and Young Sporophytes of Cyatheaceae Native to Taiwan(1)

Seven species of Cyatheaceae are native to Taiwan. Sphaeropteris lepifera, Alsophila denticulata, A. metteniana, and A. podophylla produced 64 spores per sporangium, whereas A. loheri, A. spinulosa, and A. fenicis produced 16 spores per sporangium. Spore germination was Cyathea-type, except in A. denticulata and A. metteniana. In these two species, the rhizoid formation was delayed. Gametophytes of all seven species usually underwent Drynaria-type development, but a few gametophytes of all seven species exhibited Adiantum-type development. Multicellular, scale-like hairs on the dorsal and ventral surfaces of the midrib cushion increased in size and changed shape with age. These scale-like hairs distinguish Cyatheaceae gametophytes from the gametophytes of other fern families. The first three or four fronds of young sporophytes lacked midribs. Uniseriate to multiseriate and club-shaped pluricellular hairs were intermingled on the fronds of juvenile sporophytes of all six species of Alsophila. The lacking of club-shaped pluricellular hairs on Juvenile sporophytes of S. lepifera supports the taxonomic separation of Sphaeropteris from Alsophila. The presence of 16- and 64-spored sporangia suggests two evolutionary events within Alsophila