258 THE FUNGI 



cannot be described here but greatly complicate the classification 

 of the forms. Some authors believe that the sac fungi hold rela- 

 tions to the red algse, and, indeed, have been derived from them. 



CLASS IX. THE BASIDIA FUNGI, OR 

 BA SIDIOMYCETES 



273. The basidia fungi. The Basidiomycetes come next to the 

 Ascomycetes in number of known species, which is about fourteen 

 thousand. The group takes its name from a peculiar type of 

 reproductive organ called a basidium (meaning a small pedestal). 

 The basidium (Fig. 238) is a somewhat swollen terminal cell 

 of a filament, or hypha, from which are developed a group of 

 four spores on delicate stalks called sterigmata. The hyphse of 

 the basidia fungi are divided into cells, as in the sac fungi. 



The basidium is a very characteristic structure of the higher 

 forms of the Basidiomycetes. However^ there are some types, as 

 the smuts and rusts, in which the basidium is represented by a 

 peculiar phase in the life history (the promycelium), which does 

 not at first thought seem to resemble the basidium. These 

 points can only be made clear after a study of representative 

 types, and they will be referred to later in the summary of the 

 basidia fungi (Sec. 279). This peculiarity is the basis of a classi- 

 fication of the basidia fungi into two series: (1) the Protobasid- 

 iomycetes, which are preliminary to (2) the Eukasidiomycetes, 

 or typical basidia fungi. The representatives that can be con- 

 sidered here will accordingly be grouped as follows : 



SERIES I. The simpler basidia fungi, or Protobasidlomycetes. 



1. The smuts, or Ustilaginales. 



2. The rusts, or Uredinales. 



SERIES II. The typical basidia fungi, or Eubasidiomycetes. 



3. The coral fungi, the pore fungi, the tooth fungi, the gill fungi, col- 



lectively called Hymenomycetes; and divided into several orders. 



4. The puffballs, the earth stars, the nest fungi, the carrion fungi, 



collectively called Gastromycetes, and divided into several orders. 



