52 FUNGI 



directly into a sporangium-bearing aerial hypha, the ordinary 

 spore developing into a mycelium. 



In the Ascomycetes the simplest form is yeast, which is 

 unicellular; the nucleus is diffuse and the cells are solitary 

 or they occur in temporary filaments, which result from rapid 

 cell division. Reproduction is largely by budding. Some 

 forms produce a sac or ascus which contains two or more 



FIG. 19. A bracket fungus growing from a dead stump. 



spores or ascospores, a fact which has resulted in giving the 

 name ascomycetes to the group. In other forms there is a 

 subterranean mycelium which absorbs food material. The 

 mycelium gives rise to branched, intertwined, firm, masses 

 of hyphse which grow into the air, thus elevating the asci 

 which bear the spores. 



Basidomycetes, represented by toadstools and mushrooms, 

 have mycelia from which grow an aerial structure differen- 



