Key to Orders and Families 



I. Filaments one-celled, rarely septate, typically aqua- 



tic or endobiotic ; propagation by fission or by 

 conidia, the latter usually in sporangia ; sex-cells 

 typically present, uniting to form resting-spores 



II. Filaments septate, typically saprophytic or epibi- 



otic ; conidia borne on conidiophores ; sex-cells 

 usually absent 



1. Spores in a hymenium composed of asci or club- 



shaped basidia 



a. Spores in asci 



b. Spores on more or less club-shaped basidia 



2. Conidia on conidiophores of various form, not in 



asci or on true basidia 



Phycomycetes 



I. True mycelium lacking or rudimentary 



I. Threads simple, globose to filamentous, often 

 motile ; propagating by fission or by conidia also 



a. Cells single or in colonies, never forming plas- 



modium-like masses 

 (i) Cells filamentous, not spirally twisted 



(a) Filaments motile, sheathless 



(b) Filaments non-motile, sheathed 



(2) Cells cylindric to globose, spirally twisted 

 when filamentous 



(a) Cells more or less spirally twisted 



(b) Cells not spirally twisted or curved 

 X. Cells oblong to cylindric 



y. Cells globose or cuboid 



b. Cells secreting a gelatinous matrix and form- 



ing pseudoplasmodia, passing into cysts or 

 spore-masses which are often stalked 

 2. Threads absent or slightly developed ; propagation 

 by sporangia which produce zoogonids ; sex- 

 cells rare 



II. Mycelium present, typically well-developed and 



branched ; propagation by zoogonids or by non- 

 motile conidia borne in sporangia or on conidio- 

 phores ; sex-cells usually present 

 I. Aerial fungi propagating by conidia 

 a. Conidia typically in globose to cylindric sporan- 

 gia ; mostly saprophytes ; zygosporous 



Phycomycetes 



Ascomycetes 

 Basidiomycetes 



Fungi Imperfecti 



Bacteriales 



Beggiatoaceae 

 Chlamydobacteriaceae 



Spirillaceae 



Bacteriaceae 

 Coccaceae 



Myxobactrales 



Chytridiaceae 



Mucoraceae 



