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PHARMACEUTICAL BOTANY 
mycelium is localized and gives rise underneath the epidermis to 
rounded egg-shaped spores attached to it by short pedicels. The 
spores are produced in such numbers that the space beneath is too 
confined. As the long epidermal cells of grasses run longitudinally, 
the pressure of the spore masses from within causes the epidermis to 
crack and its edges become turned back. Through the resultant 
cleft the summer spores or uredospores are thrust out. These uredo- 
spores are orange-brown in color and covered with minute spines. 
The mass of them has been called a uredinium. These spores are 
Fig. i 41.—Spore forms of wheat rust, Pucainia graminis. A, Section through 
barberry leaf showing pycnia on upper surface and aecia on lower; B, two uredi- 
nio spores; C, germinating urediniospore; D, teliosorus showing several telios- 
pores; E, single two-celled teliospore; F, germinating teliospore with four-celled 
basidium and two basidiospores; G, basidiospore growing on barberry leaf. 
(Harshberger, adapted from deBary.) 
detached from the pedicels and blown by the wind to healthy plants. 
After summer is over and dry weather comes on, an examination of 
stubble in the field (blades of grass and stems of wheat left carelessly), 
these rust-red lines are replaced by brownish-black spores called 
teleutospores (teliospores). A mass of these is known as a telium.. 
The summer stage on wheat is known as Uredo linearis. 
The autumn stage on wheat is known as Puccinia graminis. 
