MiCROSPHAERA 1^1 



Menisperimnn Canadense. The form on this host-plant has been 

 described as a distinct species, M. inciiispcnni E. C. Howe. 



Burrill (60), in his critical work on the American species of 

 Microsphaera, has maintained M. inenispcnni as a distinct species. 

 " Remarkable for the variation in structure and size. In some 

 perithecia only one ascus is found, while in others in the same 

 microscopical preparation at least seven have been seen. The 

 appendages on a single perithecium are somewhat equal in length, 

 but are often exceedingly variable in the division of the tips. 

 Sometimes there is only a single fork with two equal, straight, 

 obtuse branches, and again, the exceedingly ornamental tips fill 

 the field of the microscope with its complex scroll-work." 



I am indebted to Professor Underwood for sending me an 

 authentic specimen of M. menispcruu from the Ellis Herbarium. 

 Examination of this specimen (now in the Kew Herbarium) showed 

 that without doubt the fungus must be referred to M. aim, and, 

 judging from this specimen alone, it cannot be considered even a 

 marked form of this variable species. The specimen showed these 

 characters, mycelium evanescent, perithecia more or less scat- 

 tered, 100-135/^ in diameter, appendages 12-20, about equallin 

 the diameter of the perithecium, colorless, apex 4-6 times closely 

 and regularly dichotomously branched, tips of ultimate branches 

 regularly and distinctly recurved, asci 4-8, spores 4-8. The 

 branching of the apex of the appendages is often very ornate, but 

 corresponds exactly with that of many common American forms 

 of M. alni. From some of the characters given by Burrill in his 

 description — e, g., appendages sometimes seven times the diameter 

 of the perithecium — it seems just possible that some other plant 

 may have been under observation. However this may be, it is 

 safe to consider M. inenlspermi E. C. Howe as a synonym of 

 alni, as is seen by the characters shown by these authentic speci- 

 mens (collected by Howe), which agree, moreover, exactly with 



Howe's original description. 



There is a specimen in the Kew Herbarium labelled ''Micro- 

 sphaera, on Populus, New York, Gerard, 1 30." The fungus on this 

 is J/: aim, and the host-plant P. grandidcntata. M. alni has not 

 been reported on Popidus, and in the present case I feel doubtful 

 whether the perithecia originally grew on the leaves, or ha\-e 



M. 



