HYDNACEAE 



481 



rarely four-spored and stichobasidial and emerge from the stomata of 

 the host, sometimes intermingled with long, slender, hyaline hyphae or 

 "paraphyses." This was described rather fully by Gaumann (1922). 

 (Fig. 158.) 



The following genera have been assigned to this family but later study 

 has shown that they belong elsewhere : Micro- 

 stroma, Protocoronospora, and Urohasidium. 

 Wolf (1927, 1929) showed that the first is not 

 a Basidiomycete at all because its supposed 

 basidia are multinuclear, the mycelium lacks 

 conjugate nuclei, and the spores are not borne 

 upon the sterigmata in the manner typical of 

 the class. Wolf (1920) and Karakuhn (1923) 

 showed that the second, like the former, 

 belongs to the Fungi Imperfecti, with the 

 name properly Kahatiella. Urohasidium 

 described by Giesenhagen (1892) was shown 

 by Mason (1941) to be still another Imperfect 

 Fungus. Its proper name is Zygosporium. (Fig. 

 201B, C.) 



The relationship of this family is not 

 certain. Perhaps it represents a line derived 

 from the simplest Thelephoraceae but highly 

 modified by its extreme parasitism. 



Family Hydnaceae. These fungi are 

 mostly saprophytic. Some cause serious decay 

 of timber. The spore fruit may be small or 

 large and resupinate or shelf-like or with a 

 pileus borne on a lateral or central stipe. In 

 some forms the pileus is divided into many 

 small pilei. The consistency varies from fleshy 

 to woody and there is a great range of color. The under side of the 

 fruit body is at first smooth but as the hymenium develops it grows 

 out into hymenium-covered spines or teeth. Under the classification 

 of Fries all such fungi were classed in one family. However, Bourdot and 

 Galzin (1927) placed the genera with hyaline or light-colored spores in 

 the group Hydnes (except Irpex which they place in the Pores) and those 

 with brown spores in the Phylacteries (i.e., close to Thelephora or 

 Phylacieria). Donk (1933) places the stichobasidial forms in Tribe 

 Hydneae of the Cantharelloideae and the remaining, chiastobasidial 

 forms in the Phylacteroideae close to Thelephora, except some species of 

 Irpex placed by him in the Polyporoideae, Tribe Daedaleae. Irpex is 

 placed by Singer (1944) in the Polyporaceae, and by Murrill (1907) in 



Fig. 158. Polyporales, 

 Family Exobasidiaceae. Ex~ 

 obasidium vaccinii (Fuckel) 

 Wor. Basidia in various 

 stages of maturity emerging 

 through the epidermis of the 

 host leaf. (After Killermann, 

 in Engler und Prantl: Die 

 Nattirlichen Pflanzenfami- 

 lien, Zweite Auflage, vol. 6, 

 pp. 124-288, Leipzig, W. 

 Engelmann.) 



