UREDINALES 



559 



ribicola (Colley, 1918), C. Comptoniae, C. pyriforme (Adams, 1919), 

 Uromyces Caladii (Christman, 1905; Fromme, 1914), Puccinia Caricis and 

 P. Pruni-spinosae (Kursanov, 1922), the hyphae of the knot are arranged 



Fig. 376. — Uromyces Poae. 1. Young aecidium. Fertile cells above and sterile 

 degeneration cells below. 2. Immature aecidium with peridium, Per, and immature 

 aeciospores, Sp. ( X 415; after Blackman and Fraser, 1906.) 



in a more or less palisade-like structure and are usually perpendicular to 

 the plane of the epidermis, in a few species pointed toward the middle of 

 the top. The terminal cells (in P. Pruni-spinosae, a few intercalary cells) 



