ON WILLOW 



341 



19 fi; epispore lt|- — 3^/x thick, without perceptible germ-pores; 

 paraphyses capitate, with a thin pedicel, occasionally clavate, 

 thickened (up to 10 /x) above, hyaline, 35 — 80 x 15 — 24 //. 



Fig. 257. M. Larici-epitea. 

 Caeoma on Larch leaf, x 2 

 (one of Plowright's cultures 

 from S. tin erect). 



Fig. 258. M. Larici-epitea. 

 Uredospores and para- 

 physes, on S. viminalis. 



Teleutospores. Sori amphigenous, covered by the epidermis, 

 at length dark-brown, sometimes tinged round with greyish- 

 blue or violet, \ — 1 mm. diam., densely clustered or confluent ; 

 spores prismatic or subclavate, rounded at both ends, occasion- 

 ally narrowed above, 20 — 50 x 7 — 14 p, ; epispore clear-brown, 

 uniformly thin, without an evident germ-pore. 



Cseomata on Larix europaea ; uredo- and teleutospores on 

 many species of Saline. The teleutospores in October and 

 November. (Figs. 257, 258.) 



This species is one of the, most complex of all the Melampsoracese ; it 

 has been divided into about eight biological races, all of which have their 

 cseoma on Larch, while the other spore-forms are specialised to certain 

 species of Willow. It is recorded on the following British Salices for 

 other countries, but it is not possible as yet to say on which of these it is 

 found in this country : IS. aurita, Caprea, cinerea, fragilis, Smithiana, 

 viminalis for the typical form ; nigricans for the form M. Larici-nigricantis 

 Schneider ; purpurea for the form M. Larici-purpureae Schneider ; and 

 reticulata for M. Larici-reticulatae Schneider. Morphological differences 

 between these forms are not discoverable. 



The teleutospores germinate in the spring following after their forma- 

 tion. The teleuto-sori are formed under the epidermis, and appear to 

 start usually just below a stoma ; they often occupy entire areas bounded 

 by the veins. This description is taken mainly from Fischei 1 . The 

 teleutospores are distinguished from those of M. Larici-Caprearum by the 

 total want of thickening at the apex. Plowright produced the cseoma on 

 Larch from the teleutospores on Salix cinerea, May 24th, 1900. 



