Observations on gametophytes and juvenile sporophytes of Archangiopteris somai Hayata (Marattiaceae), an endangered fern in TaiwanObservObservations on gametophytes and juvenile sporophytes of Archangiopteris somai Hayata (Marattiaceae), an endangered fern in Taiwan

Archangiopteris somai is an endemic eusporangiate fern in Taiwan. It is classified as an endangered species because there are only a few small populations. In culture, spores germinated two weeks after sowing. Gametophyte development is “Marattia”- type. Gametophyte shape changed from circular, to cordate to branched. Antheridia and archegonia appeared 8 and 12 months, respectively, after spores were sown. Antheridia occurred in the cushion on the dorsal and ventral surfaces of gametophytes; archegonia were observed on the ventral surface only. On hermaphroditic gametophytes, antheridia and archegonia were usually intermingled. Both types of gametangia were eusporangiate. After 13 months culture, sporophytes began to form. Each gametophyte had several archegonia and only one sporophyte was produced per gametophyte. The first sporophyte frond was simple and had pinnate venation. After 3 years culture, only 3% of the gametophytes produced a sporophyte. It took a minimum of 13 months from spore sowing for a sporophyte to be produced by a gametophyte. Increasing the wild population likely will be slow and difficult.