FIG. 153. Wheat rust (Puccinia graminis) 



A, portion of stem of wheat with rust spores in groups, or sori; B, sectional view of 

 a sorus, with young uredospores (?/?/) and mature uredospores (u), stalks (st),&nd my- 

 celium (m) within the stem tissues; C, red-rust spore (uredospore) with stalk (st) 

 sending out infection hyphae (m) ; D, two-celled black-rust spore (teleutospore, t) 

 with greatly thickened cell wall and stalk (st) ; E, germination of the upper spore 

 cell of the teleutospore (t) to form the promycelium (p), hearing disseminating 

 spores (sporidia, s) F, section of barberry leaf showing the aecidium cup with 

 spores (s), the wall of the cup, or peridium (p), and the upper and lower epidermis 

 of the leaf (e and e 2 ). Adapted from Duggar's " Fungous Diseases of Plants " 



