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A jMonograph of the Common Indiana Species of Hypoxylon. 



Charles E. Owens. 



It is the purpose of this paper not to present an exhaxistive treatise 

 on the genus Hypoxylon. but to give a brief account of the habit and 

 habitat of these finigi as the writer has observed them, together with a 

 Ivey to the species which have been collected in this State. Descriptions of 

 the species covered by the key have also been included. 



The Hypoxylons, like most other fungi, have a vegetation phase which 

 grows hidden in the substratum, and a fruiting phase which grows on 

 the surface of the host for the purpose of facilitating the dissemination of 

 Ihe spores. The essential part of this fruiting body consists of from one 

 to many perithecia which contain the spore-bearing asci. The perithecia 

 are usually aggregated in clusters and imbedded in a carbonaceous crust 

 known as a stroma. The stroma is more or less conspicuous and varies 

 greatly in form and size. Sometimes it may take the form of a broadly 

 effused crust several inches or even many feet in extent ; again it may be 

 a globose, subglobose, or hemispherical structure varying in size from a 

 single perithecium approximately 1 mm. in diameter, to a large stroma 

 1 to 2 cm. in diameter and containing numerous perithecia. The perithecia 

 are usually arranged perii)herally in a single, regular or irregular layer. 

 Sometimes, however, they are crowded into several more or less irregular 

 layers, so that the spore-bearing layer of the stroma may be several times 

 the thiclvuess of a single peritliecium. The stromata are usually of a 

 carbonaceous nature, but sometimes they are woody or corky-fibrous. The 

 color of the substance is generally dark-brown or black ; while that of 

 the surface exliibits a range from whitish or gi'ay, through various shades 

 of red, ferruginous and purple, to black. 



Without exception, the species of this genus are saprophytic and live 

 \'.\H>n the dead trunks, branches and I'otten wood of various kinds of trees. 

 They prefer the shade and nmisture of the woods and are seldom found in 

 the open where they would be exposed to direct sunlight for a large part 

 of the day. Certain species, however, ai'e sometimes found around the 

 edge of woodlands where they are not shaded at all times. This is es- 



