JRONARTIUM. 



381 



host-plants, and several species produce blister-rust on the bark 

 of species of pine. 



Cronartium asclepiadeum (Willd) (U.S. Anierica). I'redo- 

 and teleutospores occur on Ci/uanchum Vincetoxicum (perhaps 



Fig. 214. — Cronartium asdcpiiuhurn on Cynanchum Vincetoxicum. The urudo- 

 sori show as spots, the teleutospore-sori as processes on the leaves, (v. Tubeuf 

 del.) 



also on Gentiana aschyiadca). The aecidial stage, known as 

 Peridcrmium Cornui Eostr. et Ivleb. produces a blister-rust on 

 the bark of Finus sylvcstris. 



Fio. 215. — Cronnrtium rwlepindtuin. Section of a 

 C'l/nanck urn leaf. The leaf- parenchyma is permeated with 

 mycelium, and sori are formed on the lower epidermis. 

 A, urcdo-sorus ; B, teleutospore-sorus, many spores of 

 which have germinated and given off promycelia with 

 sporidia. (v. Tubeuf del.) 



Brown spots may l)e found on the leaves of the Cywiarhum'^ 

 during July, August, and September (Fig. 214). On examina- 

 tion of the spots with a lens, the leaf-epidermis will be found 



^ A very common plant in Europe though not indigenous to Britain. (Kdit.) 



