316 USTILAGINEAE. 



empty (Fig, 172). Spore -formation causes the parenchyma of 

 the stem to be destroyed in strips, along which rupture takes 

 place, and the haulm, losing its rigidity, falls over. The balls 

 of spores consist of one or two smooth spores enclosed by 

 companion-cells. Germination takes place easily in water, and 

 a circle of cylindrical conidia are produced from the end of 

 each promycelium. The conidia, without becoming detached, 

 give off a lateral germ- tube. The mycelium does not hibernate. 



While this smut does not occur on cereals so commonly as 

 species of Ustilago and Tilletia, still it may sometimes cause 

 severe loss. Treatment of seed by Jensen's hot-water method, 

 or by a copper sulphate steep, may be resorted to, but the 

 results have not as yet been always successful. 



The only other smut of rye is Ustilago secalis in the grain, 

 and it is only rarely found. Winter, however, considers rye 

 amongst the host-plants of Urocystis agroinjri. 



Urocystis agropyri (Freuss.) (Britain and U.S. America). Leaves and 

 hauhiis of Triticnm repens, Arrhenatherum elatms, Festuca rubra, and 

 Bromus inermis are the liabitat of this species. 



U. festucae. Another species distinguished by I"le on Festuca. 



U. Ulei Magn. In leaves, more rarely in inflorescences, of Poa pratensis. 



U. luzulae Schroet. On leaves of Luzula pilosa. 



U. colchici (Schlecht.). On leaves of Colchicum autumnale, 

 Muscari comosum, M. racemosum, Paris quaclrifolia, and Scilla 

 hifolid. (Britain and U.S. America.) 



U. cepulae Frost.^ (U.S. America). Onion-smut. This 

 frequents the green leaves and subterranean scales, producing 

 pustules, which break when mature and allow the black spore- 

 powder to escape. 



U. ornithogali Korn. frequents leaves of Oniithogalum umhellatum. 



U. gladioli (Req.) is found in tubers and stems of Gladiohis (Britain). 



U. anemones (Pers,). (Britain and U.S. America.) Anemone- 

 snmt. This may be found in leaves or stems of many 

 lianunculaceae: Anemone Hepatica, A. nemorosa, A. ranunculoideSy 

 Pulsatilla alpina, P. vernalis, P. Pennsglvanica, P. acuiiloba, P. 

 haldensis, etc. ; also on Atragene alpina, Aconitum Leucoctonum, 

 Actaea spicata, Hellehoriis viridis, H. niger, Ranunculus Ficaria, 

 R. htdhosus, R. repens, R. sardous, Eranthis hiemalis. Brefeld 

 says the spores germinate in water, after resting for half-a-year. 



^ R. Tliaxter. Report of Comiecticut Ayric. Exper. Station for 1889. 



