104 THE FUNGI WHICH CAUSE PLANT DISEASE 



Key to Subfamilies and Geneka of Mucoracese 



Sporangia! membrane cuticularized and per- 

 manent above, thin and fugaceous be- 

 low Subfamily I. Piloboleae. 



Sporangiophore of equal size throughout; 



spore mass not forcibly discharged . . . Pilaira. 

 Sporangiophore swollen beneath the spo- 

 rangium; spore mass forcibly dis- 

 charged at maturity Pilobolus, p. 105. 



Sporangial membrane thin and fugaceous 

 throughout 



Sporangia all similar Subfamily II. Mucoreae. 



Mycelium differentiated into a colorless 

 vegetative and a colored aerial re- 

 gion 

 Aerial myceUum stoloniferous, zygo- 

 spores formed in the substratum 

 Sporangiophores arising from the 



nodes 1. RMzopus, p. 105. 



Sporangiophores arising from the 



internodes 2. Absidia. 



Aerial myceUum not stoloniferous; 

 zygospores aerial 



Sporangiophores simple 3. Spinellus. 



Sporangiophores dichotomously 



branched 4. Syzygites. 



Mycelium undifferentiated 



Mycelium gray or brown; suspensors 

 smooth 



Sporangiophores simple 5. Mucor, p. 106- 



Sporangiophores variously branched 



Sporangia borne apically on the 



sporangiophore and its 



branches 



Zygospores formed from equal 



gametes 6. Calyptromyces. 



Zygospores formed from un- 

 equal gametes 7. Zygorhynchus. 



Sporangia borne only on the 

 lateral, circinate branches of ^ 

 the sporangiophore 



