﻿132 BOTANICAL GAZETTE [February 



usually concentrically disposed on the convex and upper surface 

 of the ''caps;'' pseudoperidium none ; aecidiospores in chains, 

 caeoma-wise, spores linear-oblong to subovate, very irregular 

 in shape and size and often angular or prolonged into a point at 

 one or both ends ; walls thick, densely granular, light brown, 

 13-20 by 30-40 yx; germ pores 4, equatorial, faint. 



Uredo- and teleutosori subepidermal, on both sides of the 

 leaves and sparingly on the leaf stems. 



II. Uredosori orbicular to elliptical, averaging 0.3-0.5 



mm 



sometimes 0.6-0.7'"°^ in diameter, cinnamon-brown, or chestnut- 

 brown w^hen many paraphyses are present ; uredospores oval to 

 obovate to fusiform, 17-24 by 32-45 /x, fulvous, darker and thick- 



■ 



ened somewhat at the apex, spinulose ; germ pores four, equa- 

 torial ; paraphyses many, capitate; heads intensely dark brown, 

 15-20 by 20-25/1; pedicels stout, hyaline to fulvous, 5 by 



20-35 /^* 



III. Teleutosori black, scattered, large, 0.75-I-2 "^"^ in diam- 

 eter; teleutospore heads intensely dark brown, opaque, apex 

 depressed, smooth, ioo-150/r in diameter; 6-10 spores in cross 

 section, each spore 15-20 by 40-45 a^, apex intensely brown 

 for 12-14 /i, remainder of spore semi-hyaline; cysts hyaline, 

 many, beneath the entire head, pendent, ovate to spheroid, 

 swelling and bursting in water; pedicel hyaline, compound, or 

 of separate hyphae, short, deciduous. 



On Prosopis jidiflora : Austin, Texas, May 8, 1901, no. Q09 (type of 

 aecidial stage); Aug. 26, I901, no. 1031 (type for II and III); July 2, igoo, 

 no. 25 ; Oct. 25, igoo, no. 10; Denton, Texas, June 12, igo2 (I), and Oct. 

 20. igo2 (III); College Station, Texas, July-Aug. (II), 1888, leg. Pammel ; 

 Texarkana, Texas, Nov. 5, 1899 (III), Holway \ San Bernardino, Cal.; leg. 

 S, B, Parish, no. 2541 (type of R. Holwayi Diet.). 



The galls appear soon after the leaves are expanded. In about two 

 weeks the aecidiosori began to open; the galls persist on the trees for 

 several weeks and then usually fall off. They are followed in about two 

 weeks by the uredosori which do not form galls. The uredospore stage con- 

 tinues till October, when the teleutospores begin to appear and these con- 

 tinue till frost kills the leaves of the host. 



The rust usually infests trees that are in a low, damp situation, as on 

 the margin of a stream or in a ravine. The "caps" usually appear before 

 the galls and seem to be confined to the leaflets, while the gaMs are on the 

 leaf stems and young branches. 



