USTILAGO. 



279 



Ustilago maydis (D.C.)^ (Britain and U.S. America).^ This 

 smut of Zea Mais produces large and conspicuous deformations 

 on leaves, leaf-sheaths, stems, roots, and all parts of the male and 

 female flowers. These are whitish, 

 gall-like swellings and blisters, 

 containing a mass of gelatinous 

 mycelium, from which spores are 

 produced. The swellings may- 

 attain to the size of a fist, or 

 even larger. The spores appear 

 at first as dark olive-green 

 masses seen through the lighter- 

 green outer tissues of the host- 

 plant. When mature the spore 

 masses cause rupture of the 

 enclosing host-tissues, and escape 

 as a dusty powder. The spores 

 are dark-brown in colour, irregu- 

 larly spherical in shape, covered 

 with delicate spines, and measure 

 9-1 2m in diameter. They re- 

 main capable of germination for 

 many years. 



On being sown from the host- 

 plant directly into water, very 

 few spores germinate at once, 

 yet if sown in the following 

 spring they readily do so. In a 

 nutritive solution {e.g. plum-juice 

 gelatine) an abundant germina- 

 tion may be obtained at any 

 time. A delicate hyaline hypha 

 is given out first, and after be- 

 coming divided up by several cross-septa, it proceeds to abjoint 

 conidia from various places. The conidia sprout in the gelatine 



Pig. 

 Maize. 



150. — Ustilago Tnixytiis in head of 

 (v. Tubeuf phot.) 



'American Literature: U.S. Dept. of AgrictUture Report, 1889, p. .380, with 

 description and recommendations as to treatment. Also Ohio A gric. Exper. Stat. 

 Bulletin, Vol. in., p. 271, 1890. 



^The principal authorities for the occurrence of the Ustilagineae in Britain 

 and the United States are Plowright [British Ustilagineae, 1889), and Farlow 

 and Seymour [Host-index of Fungi of U.S. America, 1891). (Edit.) 



