THE THELEPHORACEAE OF NORTH AMERICA. X^ 



Hymenochaete 

 edward angus burt 



Mycologist and Librarian to the Missouri Botanical Garden 



Professor in the Henry Shaw School of Botany of 



Washington University 



HYMENOCHAETE 



Hymenochaete Leveille, Ann. Sci. Nat. Bot. III. 5 : 150. 

 1846; Berk. & Curtis, Linn. Soc. Bot. Jour. 10:333. 1868; 

 Cooke, Grevillea 8 : 145. 1880; Sacc. Syll. Fung. 6 : 588. 1888; 

 Massee, Linn. Soc. Bot. Jour. 27 : 95. 1890 ; Engl. & Prantl, 

 Nat. Pflanzenfam. (1:1**): 121. 1898. 



Fructifications coriaceous to hard, of varied form from 

 stipitate to resupinate; hymenium even or rarely granular, 

 containing slender, somewhat conical, colored setae between 

 the basidia; basidia simple; spores hyaline, even. 



There is no type species, for this genus is a fine example of 

 basing the generic conception upon a group of thelepho- 

 raceous species, some stipitate, some dimidiate, some reflexed, 

 and some resupinate, which agree in having setae in the 

 hymenium. 



In addition to the distinctive morphological character of 

 elongated, conical setae in the hymenium, there is also a chem- 

 ical substance in the tissue of all the species of Hymenochaete 

 which I have studied, that causes an immediate darkening of 

 sections when dilute potassium hydrate is brought in contact 

 with them. This darkening is so great as to make the sec- 

 tions too opaque for study if more than a mere trace of this 

 usually useful reagent is employed to swell the sections. One 

 has to use instead lactic acid to have the sections remain clear 

 enough to show their fine structural details. The greatly 

 elongated, colored cystidia and conducting organs which are 

 present in the deeper tissue and curve into, or even protrude 

 above, the hymenial surface in some species of Stereum, as, 

 for example, S. umhrinum, S. abietinum, S. glaucescens, etc., 



^ Issued December 23, 1918. 

 Ann. Mo. Bot. Gard., VOL. 5, 1918 (301) 



