KEY TO CLASSES AND SUBCLASSES OF PERFECT FUNGI 33 



KEY TO THE CLASSES AND SUBCLASSES OF PERFECT FUNGI 



I. Mycelium coenocytic if present, if absent not rei^roducing by budding or 



fission. Class PHYCOMYCETES 



II. Mycelium septate if present, if absent reproducing by budding or fission. 



A. Sexual spores exogenous. Class BASIDIOMYCETES 



B. Sexual spores endogenous. Class ASCOMYCETES 



C. Sexual spores unknown. Class FUNGI IMPERFECTI 



Subclasses of Phycomycetes 



I. Mycelium absent or rudimentary. Subclass ARCHIMYCETES 

 II. Mycelium well developed. 



A. Sexual reproduction heterogamous; non-sexual spores motile or developing 

 motility. Subclass OOMYCETES 



B. Sexual reproduction in most cases isogamous; non-sexual spores non-motile. 



Subclass ZYGOMYCETES 



Subclasses of Ascomycetes 



I. Asci produced from oogonium directly, or after multiplication by budding of 



diploid cells. Subclass PROTOASCOMYCETES 



II. Asci borne on ascogenous hyphae. (Euascomycetes) 



A. Asci distributed irr.egularly in a closed perithecium. 



Subclass PLECTOMYCETES 



B. Asci arranged in a hymenium. 



1. Hymenium in an apothecium. Subclass DISCOMYCETES 



2. Hymenium in a perithecium. Subclass PYRENOMYCETES 



Subclasses and Orders of Basidiomycetes 



I. Basidia alwavs simple; basidiospores on germinating producing mycelium di- 

 rectly. " Subclass HOMOBASIDIOMYCETES 



(Mushroom and allies) 

 II. Basidia septate or deeply divided or arising from a teliospore or probasidium. 



Subclass HETEROBASIDIOMYCETES 



A. Basidiocarp well developed; usually saprophytic. 



Order TREMALLALES 



B. Basidiocarp represented by a mass of probasidia, often compound (telio- 

 spore) ; always parasitic on vascular plants. 



1. Basidiospores borne on sterigmata, never reproducing by budding. 



Order UREDINALES 

 (Rusts) 



2. Basidiospores sessile on epibasidia, usually capable of reproducing by 

 budding. Order USTILAGINALES 



(Smuts) 



