PHYCOMYCETES - 355 



form, branched haustoria ; conidiophores solitary or 

 fasciculate, emerging through the stoma of the host, 

 dichotomously branched, ultimate branchlets often acute 

 and curved ; conidia ovate or elliptical, not papillate at 

 the apex, giving off a lateral germ-tube on germination ; 

 oospores globose or subglobose, epispore smooth or 

 variously ornamented. 



Epispore of oospore rugulose or netted. 



Peronospora trichotoma, Massee, Journ. Linn. Soc. 

 (.Bo/.), xxiv. 45, 2 figs. (1888). Mycelium thick, haustoria 

 clavate; conidiophores fasciculate, 2-3 times trichoto- 

 mously divided; conidia small, obovate, or subglobose, 

 i2Xio/xj oospore globose, epispore brown, with ridges 

 anastomosing to form an irregular network, 35-40 p.. 



Peronospora parasitica, De Bary, Ann. Set. Nat., ser. iv. 

 vol. xx. p. no (1863). Mycelium thick, much branched, 

 haustoria numerous, branched ; conidiophores stout, 

 flaccid, irregularly 5-8 times dichotomous or trichotomous, 

 branches always repeatedly bifurcate, the last two orders 

 of branches slender and curved ; conidia broadly elliptical, 

 20-22x16-20 n, apex very blunt, pure white; oospores 

 globose, 26-43, smooth or slightly rugulose, pale yellowish- 

 brown. 



Peronospora effusa, Rabenh., Herb. Myc., Ed. i., 1880. 

 Forming effused, greyish spots ; conidiophores fasci- 

 culate, emerging through the stomata, short, thick, 2-7 

 times dichotomously branched above, ultimate branch- 

 lets thick, shortly subulate, curved downwards; conidia 

 elliptical, pedicellate, pale dingy lilac, 25-35x15-24 /*; 

 oospores globose, epispore clear brown, more or less 

 irregularly wrinkled, 25-40 p,. 



