BAS1DIOMTCETES. 



149 



the Berberidaceae. The teleutospores, developed on the Grasses, 

 hibernate on the dried portions of their host, and in the succeeding 

 year each of the two cells of the teleutospore may develope a 

 basidium with four basidiospores (Fig. 146 D, c). The basidiospores 

 are distributed by the 

 wind, germinate quickly, 

 and only proceed to fur- 

 ther development on Ber- 

 beris or Mahonia. The 

 germ-tube bores through 

 the epidermis of the Bar- 

 berry-leaf, and forms a 

 mycelium in its interior, 

 its presence being indi- 

 cated by reddish-yellow 

 spots on the leaf. After 

 6-10 days the flask-shaped 

 apermogonia appear (Fig. 

 147 B ; C, a; conidia in 

 Fig. 147 D) and a few 

 days later the cup-shaped 

 cecidia (Fig. 147 A ; C, c, 

 d, e). The former are 

 generally on the upper, 

 and the latter on the ' 

 under side of the leaf. The 

 orange - coloured aecidio- 

 spores scatter like dust, 

 and germinate only on 

 Grasses ; the germination 

 takes place in about two 

 days when placed on any 

 green part of a Grass. 

 The germ-tube enters the 

 Grass - leaf through a 

 stoma ; a mycelium is de- 

 veloped in the leaf, giving 

 rise to a small, oval, rust-coloured spot (Fig. 146 A) ; in about 6-9 

 days the epidermis is ruptured over the red spot, and numerous 

 reddish-yellow uredospores, formed on the mycelium, are set free. 

 The uredospores (Fig. 146 B) are scattered by the wind, and can 



FIG. 146. Puccinia 



graminis. 



