40 CONFERVALES 



1. Conidia borne successively on conidiophores 



little different from the hyphae Pythiae 



2. Conidia borne on highly differentiated conidio- 



phores Peronosporae 



Subfamily Pythiae 



A. Sporangia asymmetric, the insertion eccentric Pythiogeton F 194 



B. Sporangia symmetric, the insertion centric 



1. Wall of sporangium smooth; zoospores present Pythium 7:270; S 104, F 195; 3 



2. Wall of sporangium echinulate; zoospores lack- 



ing Trachysphaera F 209 



Subfamily Peronosporae 



A. Conidiophores slender, with long slender branches 



1. Conidiophore growing after the formation of 



the first conidia, producing new joints Phytophthora 7:237; S 113, 



F 199; 4 



2. Conidiophore not proliferating 



a. Conidia papillate at tip 



(1) Conidia on sterigmata arising from irregu- 



lar disks 



(2) Conidia on sterigmata without disks 



b. Conidia not papillate at tip 



B. Conidiophores stout, with short thick branches 



or swollen and sterigmate at tip 



1. Conidiophores with short thick branches Sclerospora 7:238; S 114, F212; 



4 



2. Conidiophores with a sterigmate vesicle at tip Basidiophora S 114, F 214; 4 



Bremia 7:243; S 116, F 219; 4 

 Plasmopara 7:239; S 115, F215; 



4 

 Peronospora 7:244; S 117. 



F221; 4 



Subfamily Albuginae 



One genus 



Albugo 7:233; S 110, F 188; 4 



Order 4. CONFERVALES 



Typically multicellular filamentous algae, propagating by zoospores and repro- 

 ducing by the union of isogametes, or by heterogametcs borne in antherids and 

 oogones; two small fungous families. 



Key to Families 



A. Filaments fastigiately or corymbosely ramose; 



reproduction by isogametes Blastocladiaceae p. 40 



B. Filaments usually simple; reproduction by 



heterogametes in antherids and oogones Monoblepharidaceae p. 41 



Family 11a. BLASTOCLADIACEAE 



Fitzpatrick 130; Minden 601 



Mycelium either fastigiately ramose and constricted, without rhizoids, or with 

 a thick trunk, corymbose branches and rhizoids; propagation by sporangia and 

 zoospores; reproduction by isogametes producing a biciliate zygote. 



