BASIDIOMYCETES (p. 64)ivf is." if; So; ss.' U; es; eo' " 



This class is distinguished from all others by its basidium, which 

 typically is a sporophore bearing on its distal end short stalks, 



the sterigmata, usually four, 

 on which are borne spores, 

 basidiospores, one on the 

 tip of each sterigma. Fig. 

 215. In the great ma- 

 jority of genera the basidia 

 are typical and are clearly 

 recognizable as such. 



In many of the lower 

 basidiomycetes the basidia 

 deviate somewhat from the 

 typical form. Thus in the 

 Hemibasidii, the smut 

 fimgi, the basidia are not 

 typical in that they always 

 arise from chlamydospores, 

 not directly from the my- 



FiG. 215.-The typical basidium with sterig- Celium, FigS. 217, 231, and 

 mata and spores in different stages of de- that they may produce more 

 velopment. After De Bary. , , , , , , 



than the normal number 



of four sporidia and these often from lateral, not terminal 



sterigmata. 



The basidia in the large group of rust fungi are also atypical. 

 The myceUum of the Basidiomycetes is septate and branched, 

 and is always well developed. It is often found invading cells 

 several meters from the sporogenous structures and frequently 

 weaves together to form rhizomorphs. 



Peculiar cell connections known as clamp connections, or knee 

 joints. Fig. 287, are often found. The basidia in many genera are 



298 



