THALLOPHYTA 
OS 
en 
Or 
SUBCLASS BASIDIOMYCE TES 
This group is distinguished from other fungi by having spores 
borne on a basidium. A basidium is, typically, the swollen end of 
a hypha from which project 
four slender filaments (sterig- 
mata), each terminating in a 
single basidiospore (Fig. 370). 
Some Basidiomycetes produce 
other kinds of 
spores, as well 
as basidiospores. 
The hyphe are 
like those of 
the Ascomycetes 
in, being sep- 
tate. The larg-— 
est and most 
Fig. 372. Spores of a smut (Urocystis) conspicuous of 
in tissue of onion leaf the fungi be- 
long to the sub- 
class Basidiomycetes. None of them live in water. 
The subclass Basidiomycetes is divided into 
three sections: the Hemibasidit, the Protobasidii, 
and the Hubasidii. The Hubastdit are far more 
numerous and conspicuous than the other two 
sections. They are characterized by having non- 
septate basidii. 
Hemibasidti. The Hemibasidit compose a single Fia. 373. Ure- 
order, the Ustilaginales, or smuts (Fig. 371). The iniospore stage 
fungi of this order are parasitic on various plants ©! Wheat rust 
and produce a mycelium inside the host. This 
mycelium develops very abundantly in certain 
places, and finally divides into a large number of small cells 
which round up and become chlamydospores (Fig. 372). When 
a chlamydospore germinates, it produces a short filament which 

(Puceinia gra- 
minis) (X 4) 
