316 BOTANY. 



cinia alone from forty to fifty species in the United States. They at- 

 tack many species of Phanerogams, but are scarcely known as para- 

 sites upon Cryptogams. The first stage was long known as the genus 

 jtEcidium, and under this many supposed species were described, and 

 this is still the case in all English systematic works ; in the same way 

 the second stage gave rise to the supposed genera, Uredo, Trichobam, 

 etc., and even thes*e are, to a great extent, retained in the ordinary 

 /books, although their autonomy was long since disproved. 



(e) One of the best known species of this order is that which appears 

 upon wheat, oats, and some other cultivated grasses, producing, or 

 rather being, the disease known as Rust (Puccinia graminis). It ap- 

 pears in the spring upon the leaves of the Barberry, developing there 

 the secidiospores (conidia), and constituting what for a long time has 

 been known as the Barberry Cluster-Cups, or Barberry Rust (Fig. 216, 

 A and I). Later iu the season, and usually after the Cluster-Cups 

 have entirely disappeared from the Barberry, the uredo stage begins 

 to make its appearance, first upon the leaves, and then upon the sterna 

 of the wheat, oats, etc. ; at first it may be detected by the pale yellow- 

 ish or whitish spots on the leaves ; these mark the places where the 

 uredospores are beginning to form beneath the epidermis. Within a 

 few days the uredospores (Fig. 216, III., ur) break through the epider- 

 mis and expose long lines of the orange-red spores. By the quick ger- 

 mination of the uredospores, first produced, the fungus is greatly 

 increased, so that frequently the host plant is destroyed before reach- 

 ing its maturity. This stage is known popularly as the Red Rust of 

 wheat, oats, barley, and other similar grasses. Still later in the season, 

 and usually after the ripening of the host plants, the dark-colored 

 teleutospores (Fig. 216, II.) appear in long black lines, sometimes upon- 

 the leaves, but more frequently upon the stems, and in ordinary 

 cases upon the uncut part of the stem, viz., the " stubble." This stage 

 is known as the Black Rust. The teleutospores remain upon the dead 

 Stems through the winter, and in the following spring germinate and 

 produce sporidia, which give rise to a mycelium iu the Barberry 

 leaves (Fig. 217, A, B, and C). 



De Bary,f by placing the teleutospores upon young leaves of the 

 Barberry, succeeded in producing the secidium stage, thus proving 

 Barberry rust to be but a stage of Puccinia graminis. Similarly it 

 has been shown that the aecidiospores of Barberry rust will not grow 

 upon Barberry leaves, but that when placed on a leaf of wheat, oats, 



Frederick Currey. In a paper " On the Affinities of the Uredinese," pre- 

 sented to the Iowa Academy of Sciences, May, 1878, I pointed out that 

 the structural similarity of Uredinese and Ascomycetes rendered it 

 probable that the sexual organs of the former preceded the teleuto- 

 spores. I did not then know of Currey's paper, 

 f Published in Monatsber. d. Berl. Acad. t 1865. 



