72 THE FUNGI WHICH CAUSE PLANT DISEASE 



Pycnochytrium Schroter (p. 70) 



Only resting spores are known. In germination their proto- 

 plasmic contents emerges and forms a sporangial sorus. 



P. anemones (D. C.) Schr. is common on various species of 

 Anemone; P. globosum (Schr.) Schr. on the violet, blackberry, 

 maple, etc. None of the species are of any considerable economic 

 importance. 



Cladochytriaceae (p. 67) 



A branching mycelium runs through or between the cells of 

 the host drawing nourishment from many cells. Sporangia are 

 either apical or intercalary and contain uniciliate zoospores. 

 Resting spores are also produced. There are about a half dozen 

 genera and some thirty species. 



Key to Genera of Cladochytriaces 



Resting spores only known 1. Physoderma. 



Swarm spores only known 

 Intracellular and endophytic 

 Swarm spores at first ciliate, becoming 



amoeboid 2. Cladochytrium, p. 72. 



Swarm spores not becoming amoeboid 3. Pyroctonium, p. 73. 

 Living free among the hosts 



Sporangia opening by a pore 4. Amoebochytrium. 



Sporangia opening by a lid 5. Nowakowskiella. 



Cladochytrium Nowakowski^^ 



The genus contains about ten species of intercellular parasites 

 with branched mycelial threads. The zoosporangium is globose, 

 and opens by a distinct mouth which develops a tube for the 

 escape of the zoospores much as does Olpidium. Resting spores 

 are not known. 



