SAPROLEGNIALES 167 



8. Saprolegnia Nees von Esenbeck (in Carus 1823: 514). 



The genus contains about twenty species some of which are 

 common and widely distributed (Fig. 60). Keys for specific 

 separation are given by Humphrey, Coker, and von Minden. 

 Consult these authors for more detailed information. 



9. Isoachlya Kauffman (1921: 231). 



This genus was recently erected to include several puzzling 

 species whose characters place them on the border line between 

 Achlya and Saprolegnia. The secondary sporangia arise either 

 by proliferation or by lateral branching, both modes not infre- 

 quently being represented on the same main hypha. The 

 swarmspores are definitely diplanetic. As constituted by Kauff- 

 man the genus included I. toruloides I\auff. & Coker (Fig. 61), 

 /. paradoxa (Coker) Kauff, (Achlya paradoxa Coker 1914), and 

 7. fnonilifera (de Bary) Kauff. (Saprolegnia monilifera de Bary, 

 1888: 629). Coker (1923: 85) has added two new species, 7. 

 unispora Coker & Couch and 7. eccentrica Coker. Moreover, 

 he has removed the species 7. paradoxa, making it the basis 

 of the new genus Protoachlya Coker. 



10. Achlya Nees von Esenbeck (in Carus 1823: 514). 



This is the largest genus of the family, embracing twenty-five 

 or thirty species (Fig. 61). For specific separations consult the 

 keys given by Humphrey, Coker, and von Minden. 



11. Protoachlya Coker (1923: 90). 



This genus is based on a single species, P. paradoxa Coker, 

 removed by him from Isoachlya. 



12. Plectospira Drechsler (1927: 294). 



This genus includes P. myriandra Drechsler and P. gemmifei'a 

 Drechsler (1929), weakly parasitic on tomato and sugar cane 

 rootlets in the greenhouse. The oogonium is terminal or inter- 

 calary, and may be accompanied by as many as sixty-five anther- 

 idia. The sexual and asexual organs are well figured by the 

 author. 



13. Aphanomyces de Bary (Jahrh. Wiss. BoL, 2: 179, 1860). 



In the taxonomic treatment by Coker (1923: 160) eight species 

 are described. Of these A . laevis de Bary is the best known. The 

 genus corresponds to Achlya in the same sense in which Leptoleg^iia 



