THE HASlDIUiM FUXGI (BASH >I()M VCETES) ^45 



appear as hlistciy patches, much like those made Ijv the red- 

 dish spores except for the difference in t'olor. The teleiito- 

 spores are scattered o\ev tlie ground and upon -wheat and oat 

 straw. After a period of dormancy, usually lasting through 

 the winter, these spores germinate. From each cell of the 

 teleutospore in the spring there grows a small hypha (Fig. 

 199, I>}, quite resembling the one whicli grows from the smut 

 spore (Fig. 19t)). Similarly, each cell of this hypha may form 

 one of the tliui--\\"alled spores (sporuUa'). 



Piiccinia i/raminh sometimes has another stage in its life 

 cycle. In regions — as in tlie New England States — -where 

 a slirub kno\\n as barberry is connnon, the sjDoridia -when 

 alighting upon lea\-cs of the barl>erry may gvow and produce 

 ^-^'ithiu the leaf an extensive growth of mycelium. "When 

 this mycelium produces spores the}' appear in a peculiar cup 

 on the underside of the barberry leaf (Fig. 199, K). These- 

 spores being different from any of tlie three described, and 

 being formed in a cup, are called ci'ci<Jio.'<pi)rr.% or cup sjwres<. 

 ^Ecidiospores may reproduce the rust plant Tipon -^-sheat and 

 oats. A\'hen the life cycle of black rust was first being dis- 

 covered, it -\\'as thought that all four stages are necessary, 

 and that if any one stage could be destroyed, the others 

 would of course be destnyed. Therefore attempts were made 

 to kill the barljerrv plants so that a'cidiospores could not be 

 formed. About this time it was discovered that the barberry 

 stage can be omitted. Uredospores persist through the winter 

 in sufficient quantity to reproduce the rust upon oats and 

 wheat in the following spring. Xo satisfactory pre\-entive 

 for this fungus has been discovered. Some progress has been 

 made by learning -\\-hich varieties of -wheat and oats aie most 

 resistant to attacks by the parasite.^ 



234. Other rusts. Upon the lea-\-es and stems of carnations 

 an injurious rust (^Uromyces ciiri/ophi/Uiniis~) sometimes appears. 

 Asj^aragus rust (^Piiceinia Asparai/i^, probably introduced into 

 this country from Europe but a few years ago, is now generally 



1 "Rusts of Cereals,-' Bulletin 109, S. Dak. Agr. Exp. Sta., 1908. 



