Abstract: The gametophyte development of the fern Pteris biaurita and the effects of antheridiogen secreted by the mature gametophyte of P.biaurita on the spore germination and gametophyte development of Ceratopteris thalictroides in darkness and light conditions were investigated. The results indicated: (1) The spores are dark brown, trilete. The spore germination is of the Vittaria type. The pattern of the prothallial development belongs to the Ceratopteris type. No trichome is produced during the gametophyte development. It is discovered that the gametophytes of P.biaurita can produce antheridia but can not produce archegonia in any cultural conditions. When the sowing density was appropriate, apogamous reproduction occurred in the mature gametophyte. (2) In light condition, the antheridiogen of P.biaurita could promote the spore germination of Ceratopteris, but in dark condition, the antheridiogen inhibited the spore germination of Ceratopteris. However, the effect of either promotion or inhibition was not significant. (3) In light condition, the antheridiogen of P.biaurita could delay the formation of the notch of gametophyte (i.e. the meristem) of Ceratopteris. However, it had no significant effect on the morphology and sex differentiation of gametophyte. In dark condition, the antheridiogen of P.biaurita exhibited significant effects on the morphological development of Ceratopteris. The gametophyte of Ceratopteris in the dark condition produced well developed meristem in contrast to the control materials. However, it exhibited no significant effect on the sex differentiation of gametophyte of Ceratopteris. It can be concluded that the antheridiogen system in the fern P.biaurita may greatly differs from that in the fern Ceratopteris.

Key words: Pteris biaurita, Ceratopteris thalictroides, gametophyte, antheridiogen