ON COMPOSITE 



143 



22 — 28 x 19 — 24 /*, with three more or less equatorial germ- 

 pores each provided with a thickening. 



Fig. 94. P. Cirsii. Teleuto- 

 spores, on C. palustre, from 

 Hereford. 



Fig. 95. P. Cirsii. Teleuto- 

 spore and uredospore, on 

 G. lanceolatum. 



Teleutospores. Sori mostly hypophyllous only, similar, but 

 blackish-brown or black ; spores ellipsoid or somewhat obovate, 

 rounded at both ends, not thickened above, hardly constricted, 

 verruculose or merely punctate, chestnut-brown, 25 — 38 x 

 17 — 25 /it ; epispore thin; pedicels hyaline, very short. 



On Cirsium, Dupplin Castle, Perth (M. C. Cooke). On 

 G. pratense, Ballyquirke Lake, Co. Gal way (communicated by 

 J. Adams); Earlswood Lakes, near Birmingham. On G. palustre, 

 Hereford, Seckley Wood, Barnt Green, etc. Uredospores from 

 March ; teleutospores, June — November. (Figs. 94, 95.) 



There is no mention of this in Plowright's Uredinese, or in the Trans. 

 Brit. Myc. Soc. (Plowright's list), but it is probably not uncommon. It 

 occurs frequently on the radical leaves, and can be easily distinguished 

 from P. Cnici-oleracei by the presence of the uredospores and the non- 

 circinate teleuto-sori, as well as by the absence of the apical thickening. 

 Fischer records it from Switzerland on many species of Cirsium (but not 

 on those mentioned here), and also assigns to it sperrnogones on the upper 

 leaf-surface and petiole ; I have not been able to find any trace of these in 

 our British specimens. The uredospores, seen in water, sometimes 

 appear quite smooth, as Cooke describes them. The teleutospores have 

 the upper pore at the summit or at the side, the lower pore just beneath 

 the septum or lower down ; they are at times faintly granulated, at others 

 distinctly verruculose. Mesospores are rare. 



I have also a number of specimens on C. lanceolatum from Droitwich, 

 Wyre Forest, etc., bearing a great similarity to P. Cirsii-lanceolati Schrbt., 

 but the differences from P. Cirsii are so slight and elusive that, as the secidial 

 stage by which the former is distinguished has not yet been found in 

 Britain, it is better for the present to place them under P. Cirsii. 



Distribution : Europe, Siberia, Japan, North America. 



