Gametophyte development and reproduction of two Chilean fern species, Blechnum arcuatum (Blechnaceae) and Pteris semiadnata (Pteridaceae)

Abstract

In this work we studied the germination, the pattern of morphological development, and the sexual expression of two homosporous ferns living in Chile: Pteris semiadnata and Blechnum arcuatum. For this purpose, spores from different sporophytes were collected, sowed on mineral agar, and kept under controlled conditions. The maximum germination percentages observed were 82% and 91% for B. arcuatum and P. semiadnata, respectively. The germination pattern in both species corresponded to the Vittaria-type. The morphological development pattern of B. arcuatum corresponded to the Aspidium-type. Adult gametophytes of this species presented unicellular trichomes on the surface and margin of the lamina, and they behaved as female. The species Pteris semiadnata presented a Ceratopteris-type pattern of development, originating glabrous adult prothalli. In this case, both male and bisexual gametophytes were formed, and they showed an important sexual dimorphism related to their size. The presence of female individuals at first, and the sexual dimorphism evidenced the existence of an antheridiogen system. In both species, vegetative proliferations were formed on the lamina.