38 FARLOW ON GYaCSrOSPORANGIA. 



the earliest appearance of the spermogonia of the different Roesteliae, and of the appear- 

 ance of the spox'iferous masses of Gymnosporangia in limited regions. This last point I 

 think has not received sufficient attention from Europeaii botanists. Unless I am mis- 

 taken, I have seen the spermogonia of R. lacerata near the Bussey Institution, at a date 

 preceding the maturing of any of the Gymnosporangia of the neighborhood. 



Cornu ^ has called attention to the fact that Roesteliae may be made to appear out of 

 season by means of cultures. Another important fact is to ascertain how many of our 

 Roesteliae are perennial. This, at least, appears to be the case with R. uurantiaca. 

 If it should be shown that several of our Roesteliae are perennial, a fact true with regard 

 to most of our Gymnosporangia, and to grow in regions remote from species of Juniperus 

 and Cupressus, then one could not help feeling that any connection between the two 

 genera was probably accidental rather than genetic. 



EXPLANATION OF PLATES. 

 Plate I. 



Fifjs. 1-C. Gymnosporangium macropus Lk. 1, Sporiferous masses fully exjianded; 2, the same in a 

 dry condition, sliowing the linot or cedar-apjile, and tlie contracted sporiferous masses surrounded by the 

 raised coUar at the base; 3 and 4, teleutospores, with a part of their pedicels; 5 and 6, spores producing 

 promycelia and sporiilia, 6 showing a promycelium forming at the apex. 1 and 2 natural size, 3-6 mag- 

 nified 350 diameters. 



Figs. 7-11. Gymnosporangium fuscuni var. glohosum. Farlow. 7, Sporiferous masses exjianded ; 8, the 

 same contracted, and showing the knot formed; 10 and 11, spores with pedicels; 9, spore producing promy- 

 celia. 7 and 8 natural size, 9-11 magnified 350 diameters. 



N. B. 9-11 have been drawn on too small a scale, and should be enlarged one fourth in compai-ing with 

 the spores of other species. 



Plate II. 



Fi^s. 13-17. Gymnosporangium ElKsii Berk. 13, portion of a distorted branch of Cvpiressus thiiyoides 

 Avith sporiferous masses expanded ; 14-17, spores of the same ; 17, spore bearing promycelia ; 16, anomalous 

 spore forking at the tip. 13 natural size, 14-17 magnified 350 diameters. 



Fi<>-s. 18-21. Gymnosporangiutn biseptatum Ellis. 18, stem of Cupressus tkuyoides, bearing expanded spo- 

 riferous masses ; 19-21, spores of the same ; 20 producing promycelia. 18 natural size, 19-21 magnified 350 

 diameters. 



Fifs. 22-27. Gymnosporangium clavipes C. and P. 22, twig of Juniperus virginiana, with sjioriferous 

 masses expanded, and distorted, acerose leaves, to be compared with 23 whicli represents a normal brnnch; 

 24, 25, sjjores with enlarged pedicels ; 20, spore which has f.-dlen from pedicel and jiroduced |iromycelia at 

 both extremities ; 27, spore with terminal and lateral promycelia. 22 and 23 natural size, 24-27 magni- 

 fied 350 diameters. 



iBulL Soc. Bot., 1878. 



