Arthur: Cultures of Uredineae in 1909 



235 



petioles, or fruits, cylindrical, 2-3 mm. high ; peridium rupturing^ 

 at the apex, margin not splitting much, erect, peridial cells, usu- 

 ally seen in face view, broadly lanceolate, 29-40 by 70-90/x, inner 

 and side walls thick, 9-14/x, closely spinulose with spine-like 

 papillae up to Sfi long, outer wall thinner, about 3/x, sculptured 

 like the inner and side walls but with shorter papillae ; aecio- 

 spores globoid or broadly ellipsoid, 22-25 t)y 26-7,1 /x, wall cinna- 

 mon-brown, medium thick, 2-3^, finely verrucose ; pores distinct,. 

 6-8, scattered. 



On Crataegus sp., Boerne, Texas, June 12, 1908, G. G. Hedg- 

 cock. 



3. Gymnosporangium sp. nov. The chain of circumstances 

 which led up to the detection and final culture of this very in- 

 teresting species of rust is given with sufficient detail in the 

 introduction to this paper, and need not be repeated. Material 

 collected by Mr. F. D. Kern, June 4, 1909, at Leland Mich., on 

 Juniperus horisontalis Moench, was sown, June 5, on one plant of 

 Amelanchier erecta, and two plants of A. canadensis. Numerous 

 pycnia appeared on all three plants, one June 14, and the other 

 two June 16. Owing to the fact that the season was well ad- 

 vanced, and the foliage on the Amelanchier plants quite mature, 

 by the time well developed telia could be obtained in the northern 

 habitat, the leaves on all three plants used for cultures ripened 

 and fell before aecia appeared. The field collection of the pre- 

 vious autumn, however, supplied authentic material for study, and 

 the results are not open in the slightest degree to doubt. 



It is very gratifying to establish the relationship of the horn- 

 like aecia on Amelanchier, as it is now possible to distribute the 

 three very similar forms, that have heretofore gone under one 

 name, and supposed to belong to one cosmopolitan species. The 

 three species are : Gym. cornutum, with aecia on Sorhus, common 

 to Europe and America, Gym. Davisii, with aecia on Aronia, 

 known only in America, and the present form with aecia on 

 Amelanchier, also known only from America. The first two 

 have their telia on the true juniper, while the last has telia on the 

 red cedar. The new form has been studied morphologically by 

 Mr. F. D. Kern, who has drawn up the following description and 

 supplied the name. 



