On Typhulochaeta, a New Genus 

 of Erysiphaceae. 



By 

 Seiya Ito. 



(Willi Plate I.) 



In the fall of this year, Mr. K. Hara kindly sent me excellent 

 specimens of a powdery mildew parasitic on the leaf of Quercus 

 glandulifera. Examinating the fungus under a microscope, I 

 noticed at once that it is a very interesting form of Erysiphaceae 

 and it is an undescribed species apparently having characters 

 worthy of a new generic rank. 



Before giving a detailed account of this fungus, a mention 

 must be made of some important papers dealing with the 

 classification of the family which have already appeared. 



In 1851, J. H. Leveelle (1) published a classical monograph 

 of the Erysiphaceae and divided this family into two sections 

 by the number of the ascus in a perithecium, following the 

 earlier attempt of D. F. L. de Schlechtendal (14) and H. F. 

 Link (2). He arranged two genera, Podosphaera Kze. and 

 Sphaerotheca Lev., to the first section — "Sporangium unicum" 

 — and four genera, Phyllactinia Lev., Calocladia Lev. (shortly 

 afterwards changed to Microsphaera Lev.), Uncinula Lev. and 

 Erysiphe Hedw. f., to the second—" Sporangia plurima." 



In 1899, E. Palla (5) published a paper on the genus 

 Phyllactinia. He observed an interesting fact that the hyphae 

 of Phyllactinia pass through the stomata and send the hausto- 

 ria into the cells of spongy parenchyma, while those of other 

 genera form the h.austoria in the epidermal cells. By the differ- 

 ence of parasitism, the family is divided into two sub-families, 

 the Erysipheae and the Phyllactineae. 



