Types of reproductive cell in Exidia recisa and Sirobasidium intermediae

Abstract

In Exidia recisa basidiospores germinated on agar to give a branched mycelium with prostrate conidiophores forming bacilliform conidia in succession as from a phialide. The situation is compared with that in other heterobasidiomycetes. In Sirobasidium intermediae basidia were formed in basipetal succession. The basidia liberated spore-like epibasidia (sterigmata) which accumulated in large numbers as a surface slime on the basidiocarp. The very few epibasidia that germinated in situ gave rise to aerial ballistosporic basidiospores which, on agar, germinated to give a yeast phase. Spread thinly on agar, most epibasidia germinated in a variety of ways; many gave rise to aerial ballistospores; others to a yeast phase; and a few underwent repetition to form sessile blastospores. Yeast-like colonies, arising from discharged basidiospores, developed occasional aerial tufts of clamped hyphae which, on isolation, grew slowly and soon reverted to the yeast phase. In forming a yeast-like phase and in not producing conidia as from a phialide, Sirobasidium seems closer taxonomically to Tremella than to other tremellaceous fungi.