398 A TEXTBOOK OF GENERAL BOTANY 








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F rq. 378. Leaf infected with teliospore 
stage of a rust. (x 140) 

Fie. 379. Teliospore (left) and germi- 
nation of teliospore (right) with pro- 
duction of basidiospores (somewhat 
diagrammatic). (x 445) 




cases the basidiospores and 
eeciospores infect the same 
species, while in other cases 
they infect entirely differ- 
ent species. 
Urediniospores. The myce- 
lium resulting from the growth 
of an eeciospore produces ure- 
diniospores in patches on the 
surface of the host. These 
spores are single-celled struc- 
tures which occur singly at 
the tips of short stalks (Figs. 
373, 376). A urediniospore 
is capable of germinating im- 
mediately and may give rise 
to another mycelium bearing 
urediniospores. 
Teliospores and_ basidio- 
spores. After the formation 
of urediniospores has con- 
tinued for some time the 
mycelium may give rise to 
teliospores (Figs. 377, 378). 
The teliospores germinate by 
sending out short hyphe from 
each cell of the spore. At 
the end of each hypha a row 
of four cells is produced, and 
each of these gives rise to a 
single basidiospore (Fig. 379). 
Life history of rusts. In 
some species of the Uredinales 
all the forms of spores men- 
tioned above are present, and 
they ocenr in the order given. 
