TISTILAQINEM. 317 



barley, etc., they send out filameuts, wUcili pass through the stomata, 

 and give rise to a mycelium, which, in about a week, produces uredo- 

 spores. 



(/) Uredineae are easily obtained for study in either the first, second, 

 or third stage. In most species the aecidium stage occurs in spring or 

 early summer, the second in spring or summer, and the third in the 

 autumn ; in some species, however, the teleutospores are produced in 

 the spring, as in Oymnoaporangium and Puccinia Anemones. 



ig) The sporidia may be obtained by placing pieces of grass stems 

 containing teleutospores in a damp atmosphere, after soaking for a few 

 hours in water. The teleutospores should be freshly taken in most 

 cases from those whicli have remained upon the stems out-of-doors 

 during the winter. 



407.— Order TJstilaginese. The plants which compose 

 this order are all parasites living in the tissues of Phanero- 

 gams. Like the XJredinese, the TJstilaginese send their my- 

 celium through the tissues of their hosts, and afterward 

 produce spores in great abundance, which burst through the 

 epidermis. .There is, however, in many respects a greater 

 simplicity of structure in the plants of the present order 

 than in the Uredinese, and this has induced some botanists 

 to doubt their relationship to the last-named order ; how- 

 ever, it appears that the simplicity is one due rather to 

 degradation than to any essential difference in structural 

 plan. 



408. — The mycelium of the TJstilaginese is well defined, 

 and consists of thick-walled, jointed, and branching hyphse, 

 which are generally of very irregular shape.* The hyphse 

 grow in the intercellular spaces, as well as within the cell 

 cavities of their hosts. They send out suckers {haustoria), 

 which penetrate the adjacent cells much as in the Perono- 

 sporese ; these are more abundant in the compact tissue of 

 the nodes of stems than in the long-celled tissue of the in- 

 ternodes. The mycelium generally begins its growth when 

 the host plant is quite young, and grows with it, spreading 

 into its branches as they form, until it reaches the place 

 of spore-formation. In perennial plants the mycelium is 



* The following account of the Ustilaginese is based upon an article on 

 this order by Dr. A. Fischer von Waldheim, published in Pringsheim's 

 " Jahrbiicher fur Wissen. Bot.," 1869. A translation appeared in the 

 Tram^actions of tJie iP. T. /State Agricultural Society ^ 1870. 



