Erysiphe 18 



i 



drical, the 7-8 spores measure about 18 x 12 /i. Many forms of 

 £, polygoni approach so closely to all the above characters (this is 

 the case, r. g,, with the form q{ AIbb::ia (^Acacia) called by Eriks- 

 son E. Mar/ii (orma. acaciae) that it seems impossible to separate E. 

 vernalis from them. On the other hand, E. vcrualis^ shows 

 undoubted affinity with the American species E, aggrcgaia 

 on alder-catkins. E, vcnmlis has smaller perithecia, fewer, 

 smaller, less cylindrical asci, and less interwoven appendages ; oc- 

 casionally, however, the asci show a tendency to become sub- 

 cylindrical and the roundish spores are the same in both plants. 

 It is possible that, if more intermediates occur, E. aggrcgata may 

 have to be regarded as only a well marked variaty of E, polygoni 

 Ma^rnus has considered the functus sfowine on Caragana mbo- 



rescens and Colntca arboresccns as belcnii^incj to the genus 2ncro- 



sphacra, and has published it as a new species, J/, caraganac. I 

 had already seen specimens of this plant on Colntca in Syd. Myc, 

 March. 980, and on Caragana m Syd. Myc. March. 3718, and had 

 referred them to E. polygoni Professor Magnus has kindly sent 

 me very beautiful specimens (now in the Kew Herbarium) of 

 '' Microsphaera caraganae, on Caragana arboresccns Wannsee,'* 

 and after examinincr these I still feel convinced that the fungus is 

 nothing but a form of Erysiphe polygoni. None of the specimens 

 possess appendages with apical branching of the definite type found 

 in Microsphaera ; as a rule, the appendages are unbranched, and 

 the branching that does occasionally occur is always quite vague. 

 The appendages are usually about 9 in number, rather distant from 

 one another, septate, and more or less colored towards the base. 

 Occasionally the appendages are as {<t\v as four, and the coloring 

 extends almost to the apex. A i^w perithecia were observed in 

 which the appendages, 4 or 5 in number, were stouter than usual, 

 rounded at the end, and colored deep brown throughout — much 

 recalling the American form of ^. polygoni on Parnassia mentioned 

 below. As Magnus points out, there appear often among the 

 normal appendages very short rudimentary ones. This character, 

 however, as well as that of the few and distant appendages, can 

 be in no way considered peculiar to the form on Caragana and 

 Colutea as both are found in many common forms of undoubted 



w 



E. polygoni. In the present form the appendages become more 



