— i 3 o — 



patches on the under surface of the leaves and on the petioles and 

 stems. It comes to us from South America by the way of Europe, 

 and its development is rapid and destructive. 



Again the well-known ' ' Wheat Rust ' ' is another parasite be- 

 longing to the Uredineae and therefore not a distant relative of 

 the Clover disease under consideration.* 



OCCURRENCE, DISTRIBUTION AND INJURIOUSNESS. 



Uromyces Trifolii has long been known in Europe on many 

 species of Clovers and a few other Leguminosae, but has not at- 

 tracted the attention of mycologists in America until recently. 

 The form on our cultivated Clovers was no doubt introduced with- 

 in a comparatively few years, but that on certain Rocky Mountain 

 plants may be native. 



The "Rust" proper was first reported in America in 1884, by 

 Mr. Hoi way, in the " List of Iowa Uredineae " compiled by Mr. 

 Arthur. The following table is probably sufficiently complete to 

 show its present distribution in America, the host-plants, stages 

 of fungus, and localities being given : 



*Perhaps riot everyone knows that scientific men have proved experiment- 

 ally what the New England colonists seem to have been convinced of nearly 

 a century and a half ago, viz:, that the wheat-rust has several distinct stages, 

 one of which does not grow at all on the wheat plant, but on the leaves of 

 the barberry. The legislatures of the ancient colonies of Massachusetts and 

 Connecticut, as early as 1755, passed stringent laws requiring the destruction 

 of that shrub, because it had "been found by experience that the blasting 

 of wheat and other English grain, is often occasioned by Barberry Bushes to 

 the great loss and damage of the inhabitants." 



The first stage of the Wheat Rust that on the Barberry, is bright, orange 

 yellow and its spores are found inside the small membranous cups growing 

 in clusters on the under surface of the leaf. This is usually called stage I. 

 or the " cluster-cup " stage. Its spores germinate only on the wheat plant, 

 the germ-tubes penetrating the interior of its stalks and leaves. The my- 

 celium thus formed will soon send out its fruiting, — masses of yellow one- 

 celled spores, — which appear on the plant surfaces, but not in cups as on the 

 Barberry. This is stage //and is usually called the " Red Rust " of grain 

 plants. After this appears on the same plants stage III oi the fungus, ap- 

 parent to the eye in brown or blackish vertical rows of spores, which are 

 two-celled, the familiar "Brown Rust" of wheat. The connection and 

 genetic succession of the above stages of the Wheat Rust fungus have been 

 demonstrated many times over by mycologists. 



In all Uredineae, or true " Rusts," where these three stages are present, 



