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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. 141. 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, germirating 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. 



