Report of the Botanist. Ill 



That these parasites are injurious to the plants they attack is 

 manifest, since they diminish their vigor and thus impair both the 

 quantity and quality of the seed. It is this fact that makes " rust " 

 and " mildew ;" words of such terrible import to the farmer. He 

 dreads tlie advent into his grain fields of the pest they indicate, and 

 the fearful injury it is capable of inflicting upon his pecuniary interests. 



The condition of these plants known as "rust" or Trichobasis 

 generally precedes the true Puccini a development. In this state the 

 spores are of a reddish-yellow or rust color, subglobose in form and 

 simple. They have no septum, and when fully mature no peduncle. 

 But sometimes the two kinds of spores may be found intermingled 

 in the same sorus. 



In the following synopsis an attempt has been made to group the 

 species according to their affinities and to give the characters so fully 

 that the student may satisfactorily identify the species. The color 

 of the spot is given as it appears on the upper surface of the leaf, or 

 on that surface which is opposite the spore clusters. The measure- 

 ments are of moistened spores and are given in decimals of an inch. 

 They may in some cases be a little too large for dry spores. Figures 

 of the spores have been drawn b}" the aid of the camera lucida, they 

 being uniformly magnified four hundred diameters. Although the 

 spores in the same species and even in the same cluster vary within 

 certain limits, they doubtless furnish the most reliable characters for 

 the discrimination of the species. In selecting spores for illustration, 

 those were chosen which seemed to represent the prevailing form or 

 forms in each species. 



§ 1. Spores elliptical, ohtuse, not at all or hut slightly const7'icted ; 

 peduncle very shorty hyaline. 



1. P. PULCHELLA Pech. Guvrant Brand. 



Spots yellow or greenish-yellow, orbicular, rarely confluent ; 

 sori small, circinating, sometimes confluent, blackish-brown ; spores 

 .00r-.0013' long, .0006' broad. 



Upper surface of leaves of Ribes prostratu7n. North Elba, 

 Essex county. July. 



This species is as rare as it is beautiful, having been found in no 

 other locality than the one reported. It is remarkable, from the 

 fact that the sori occur only on the upper surface of the leaf. 

 These are usually arranged in two circles, one within the other, 

 and both surrounding a central sorus or cluster of confluent sori. 

 The spots are about one-eighth of an inch in diameter and nearly 

 equal. 



2. P. MEsoMAjALis B. (& C. CUntoiiia Brand. 



Spots orbicular or elliptical, dull yellowish or brown, sometimes 

 with a darker margin ; sori minute, surrounded by the ruptured 

 remains of the epidermis, clustered, frequently crow^ded, cinnamon- 



