172 



Mycologia 



The disease as it appears on the leaves of Quercus rubra L. 

 exhibits similar symptoms. 



The Fungus 



The fungus causing this disease belongs to the order Melanco- 

 niales of the Fungi Imperfecta Specimens have been submitted 

 to Professor Farlow, who has pronounced it probably the same 

 as Monochaetia Desmazierii Sacc. This fungus was originally 

 described by Desmazieres,^ who found it in France, growing on 

 dry or fading leaves of several species of deciduous oaks, and 

 also on Quercus Ilex. It developed not on fallen leaves, but on 

 those which remained on the tree. Desmazieres named the new 

 species Pestalozzia monochaeta, thus emphasizing the fact that 

 the spores terminated in a single bristle. 



Saccardo,* in the third volume of his Sylloge Fungorum, pub- 

 lished in 1884, includes this and other species of Pestalozzia 

 having one bristle under the section Monochaetia. In 1903, 

 Allescher^ in Rabenhorst's Kryptogamen-Flora raised this section 

 to generic rank, thus giving the species in question the name of 

 Monochaetia monochaeta (Desm.) Allescher. Such a name, how- 

 ever, was practically contrary to the rules of nomenclature, 

 although, indeed, the spelling of genus and species was not exactly 

 identical. Thus, later, Saccardo*' in his Sylloge Fungorum evi- 

 dently recognized the need of a further change, and consequently 

 the name appears in his work at this time as Monochaetia 

 Desmazierii Sacc. 



According to Saccardo's description of the species, the spores 

 are apparently smaller than ours. Professor Farlow has, how- 

 ever, examined the original material distributed by Desmazieres 

 himself, and finds that the spores there were immature. In mate- 

 rial distributed later by Desmazieres, which is mature, the meas- 

 urements of the spores correspond to ours. This later material 

 of Desmazieres, moreover, corresponds to his own description, and 



^ Desmazieres, J. B, H. J., Seizieme Notice sur les Plantes cryptogames 

 recemment decouvertes en France. Ann. Sci. Nat. III. 10: 355, 356. 1848. 

 * Saccardo, P. A., Sylloge Fungorum 3: 797. 1884. 



" Allescher, Andreas, in Rabenhorst's Kryptogamen-Flora von Deutschland, 

 Oesterreich und der Schweiz. ed. 2. : 667. 1903- 

 ® Saccardo, P. A., Sylloge Fungorum 18: 485. 1906. 



