THE FUNGI WHICH CAUSE PLANT DISEASE 



299 



borne on large complex sporophores composed of the mycelial 

 threads interwoven to form a false 

 parenchyma. The spores may 

 germinate by tubes or by bud- 

 ding. 



TjT)ical sexuality seems en- 

 tirely wanting, even rudimentary 

 or vestigial sexual organs, cer- 

 tainly recognizable, have not been 

 found. The group is supposed in 

 this regard, to represent the results 

 of extreme simplification; the sex- 

 ual organs to have long ago dis- 

 appeared and the simple nuclear fusions that now exist to serve 

 functionally as fertilization. 



Fig 



216. — Ustilago spores showing 

 development. After X>e Bary. 



1. Hemibasidii, p. 299. 



Key to the Subclasses of Basidiomycetes 



Chlamydospores at maturity free in a 

 sorus, produced intercalary, from 

 the mycelium; basidiospores borne 

 on a promycelium and simulating 



conidia 



Chlamydospores absent or when present 

 borne on definite stalks 

 Basidia septate, arising from a rest- 

 ing spore or borne directly on 



a hymenium 2. Protobasidii, p. 323. 



Basidia nonseptate, borne on a hy- 

 menium 3. Eubasidii, p. 393. 



Hemibasidii 



The Hemibasidii contain one order. 



,46, 47, 124, 126-129, 131, 137 



Ustilaginales 



Parasitic fungi, smut producers, mycehum consisting of hyaline, 

 somewhat septate, branched, mostly intercellular filaments, 

 practically limited to the interior of the host; at maturity often 



