AMERICAN 
JOURNAL OF BOTANY 
Vol. IV October, 1917 No. 8 
TAXONOMIC CHARACTERS OF THE GENERA ALTERNARIA 
AND MACROSPORIUM 
John A. Elliott 
I. INTRODUCTION 
Alternaria and Macrosporium are among the most universally 
distributed and most common forms of the Fungi Imperfecti, em- 
bracing, according to the "Sylloge Fungorum" of Saccardo, 41 species 
and varieties of Alternaria and 189 species and varieties of Macro- 
sporium, these numbers including some synonyms but not the new 
species which have been described since the publication of the last 
volume of Saccardo 's work. Some species, such as Alternaria solani 
(E. & M.) J. & G., A brassicae var. nigrescens Peglion, and Macro- 
sporium sarcinaeforme Cav. are well known and destructive parasites, 
but the great majority are saprophytes or have been described from 
non-important hosts. The ascigerous stages of a few species are 
known, the connection in all such cases being with the genus Pleospora. 
Even a casual survey of the literature dealing with the genera in 
question would reveal the fact that the generic names, Alternaria and 
Macrosporium, are in many cases used synonymously in dealing with 
the best known of the parasitic species. This condition could be due 
either to there being no basis for distinction between the two genera, 
or to this basis being ill defined. The studies of the writer were 
undertaken with the hope of adding to the knowledge of these two 
genera. The work was necessarily limited and the result is in no way 
of the nature of a monograph. 
II. HISTORICAL 
The genus Alternaria was described and figured by Nees (15), 
A. tenuis being the type and only species described. The description 
[The Journal for July (4: 375-438) was issued July 14, 1917] 
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