PROTOBASIDIOMYCETES 



437 



tongue-shaped bodies .5-.7.mm. high, opening by an irregular rup- 

 ture of the peridium. The spores are, according to Arthur, coarsely 



verrucose with deciduous tuber- 

 cles, except along one narrow 

 line, where tubercles fail. 



The uredospores are produced 

 in orange-yellow sori, which soon 

 fade to nearly white. They are 

 generally ellipsoidal, measuring 

 27-30 x 1 7-22 p. The teleuto- 

 spores are borne in crowded 

 waxy masses, and are at maturity 

 a chain of four basidial cells within 

 a somewhat gelatinized common 

 wall. They are sessile, 5 5-80 x 

 I5-23//,, and the cell wall at the 

 apex is generally swollen, often 

 FIG. 213. COLEOSPORWM SEXECIONIS attaining a maximum thickness 



(b after Tulasne) of 3O 4O//.. 



XXVIII. RUST OF POPLAR 

 Melampsora tremulcz Tul. 



Tulasne applied the above name to a rust of the poplar (Popuhis 

 tremuld] occurring throughout a considerable range in Europe. 

 It would seem . 

 that this name 

 would now in- 

 clude at least 

 three forms, or 

 species, as dis- 

 tinguished by 

 Klebahn, viz., 

 Melampsora Pinitorqua 

 Rostr., Melampsora 

 Larici-tremulce Kleb., 

 and Melampsora Mag- FIG. 214. MELAMPSORA TREMVLA*: UREDOSPORES 

 nusiana Wagn. These AND TELEUTOSPORES 



