210 Illinois State Laboratory of Natural History. 



The species now assigned to this genus were formerly sep- 

 arated, and a part of them, having the gelatinous material 

 more or less columnar, made to form the genus Podisoma. 

 The distinction is not properly generic, and at present most 

 mycologists unite all the species under the generic name of 

 Gymnosporangium. The European species agree in the spores 

 having a single septum, and this is usually made a characteris- 

 tic of the genus, hut some of the American species, otherwise 

 similar, have from one to six-celled spores, so that the descrip- 

 tion of the genus is necessarily extended to include them. The 

 spores are produced in the spring instead of in the autumnal 

 months, as are the teleutospores of most Uredinew; but they 

 germinate in May and June, hence have not a long period of 

 rest. The promycelium is rapidly formed, under the proper 

 conditions, from the mature spores, and sporidia are abundantly 

 produced. These latter are believed to develop only on species 

 of Pomea^ and produce the aecidial growths included under the 

 so-called genus Ewstelia. This alternation of growth has been 

 several times experimentally shown, but for the purposes of 

 this paper the secidial forms are given by themselves. The 

 mycelium of the teleutosporic form is sometimes annual, but 

 more often perennial, and produces remarkable gall-like dis- 

 tortions upon the host. 



Gr. macropus, Lk. 



Sporiferous masses aggregated in globose tufts, surrounded 

 at the base by a ring formed by the raised epidermis and sub- 

 epidermal tissue of the host-plant, orange-yellow, cylindrical, 

 acuminate, half an inch to an inch long, or at times longer; 

 spores ovate-acute, two-celled, generally constricted at the sep- 

 tum, and with a papilla at the apex, 15-20 by 46-60 ^; promy- 

 celia generally four from each cell. Mycelium annual, produc- 

 ing globose or reniform knots in the smaller branches. On 

 leaves and smaller branches of Juniperus Virginiana. (Farlow, 

 Gymnosporangia of the U. S., p. 13.) 



On Juniperus Virginiana: Union, May 15, 4705; Cham- 

 paign, March 16, 2465. 



