FUNGI 239 



In seed-bearing plants the absence of chlorophyll is not 

 uncommon, but systems of tissue are present. On the 

 other hand, in many of the lower algae the plant consists 

 of a filament composed of a single row of cells, in fact 

 structurally a hypha, but chlorophyll is present. 



KE Y TO THE ORDERS 



Aquatic, or inhabiting damp localities. Mostly minute, 

 vegetative hyphae often continuous, and not interwoven to 

 form compact tissues. Products of sexual reproduction, 

 zygospores or oospores. Asexual reproduction by conidia, 

 which often liberate motile zoospores. Phy corny cetes. 



Parasitic or saprophytic. Mostly minute fungi either 

 having a variable number of spores in an ascus, or the asci 

 are naked (not enclosed in a perithecium), or the peri- 

 thecium is rudimentary. Hemiascomycetes. 



Parasitic or saprophytic. Aerial, minute or large, some- 

 times perennial. Asci containing a definite number of 

 spores, usually eight. Perithecium always present. 



Ascomycetes. 



Obligate parasites. Promycelium of germinating spore 

 short, either divided into 3-4 cells by septa, and each 

 cell bearing one or several secondary spores; or pro- 

 mycelium not septate and bearing a variable number of 

 secondary spores at its apex. Hemibasidiomycetes. 



Saprophytes or parasites. Spores borne on basidia in 

 definite numbers, most frequently four, basidia either one- 

 celled, or transversely or cruciately septate. 



Basidiomytetes. 



A heterogeneous assemblage of minute fungi producing 



