498 



CLASS BASIDIOMYCETEAE 



,f*- 



or mixed frondose and coniferous woods. Gyrodon merulioides has an ec- 

 centric or lateral stem and the pores are formed by radiating lamellae 

 connected by numerous cross veins not quite so high as the main lamellae. 

 The pileus is reddish brown, with yellow flesh slowly turning bluish green 

 when wounded. The hymenial surfaces are yellow becoming slightly blue 

 on wounding. The spores are yellowish brown. The pores are decurrent 



somewhat on the hollow stipe. This 

 approaches closely some of the species 

 of Paxillus. (Fig. 165.) 



Family Agaricaceae. This 

 family in its broader and more cus- 

 tomary usage included those fungi 

 whose fruit bodies increased the 

 hymenial surface by the production 

 of radiating lamellae which are 

 entirely covered, or all but the edge, 

 by the hymenium. The latter may or 

 may not extend from gill to gill on 

 the interlamellar surface of the 

 pileus. The interior tissue of the 

 lamella (the trama) may continue 

 unchanged up into the pileus or the 

 pilear trama may be distinct in 

 structure, €olor, etc., from the 

 lamellar trama, paralleling the con- 

 ditions in the Polyporaceae. 

 In contrast with the Polyporaceae where the spore fruits are prevail- 

 ingly rather dry at maturity those of the Agaricaceae are mostly fleshy, 

 although some dry forms occur. In the vast majority of cases they are 

 centrally stipitate, rarely laterally so, occasionally attached laterally with- 

 out a stipe, or even partially resupinate. In size the pileus may vary from 

 a very few millimeters in diameter in some species of Marasmius to 40 cm. 

 in specimens of an exannulate form of Agaricus arvensis Schaeff. ex Fr., 

 collected by the author. A specimen of this size must be capable of pro- 

 ducing an enormous number of spores since Buller (1909) has shown that 

 a not unusually large specimen of A. campeslris L. ex Fr. can produce 1800 

 million spores. 



In general the basidia are club-shaped, varying to ovoid or cylindrical. 

 Usually four l)asidiospores are produced although species or races fre- 

 quently occur in which the number is two. In the latter case this may 

 result from the development of spore fruits on monocaryon mycelium and 

 the consequent lack of nuclear fusion and meiotic divisions in the basid- 

 ium, there being only one division and that mitotic. The spore fruit may 



Fig. 165. Agaricales, Family Bole- 

 taceae. Tylopilus felleus (Bull, ex Fr.) 

 Karst. (Courtesy, Atkinson: Studies of 

 American Fungi, Ithaca, N. Y., Andrus 

 and Church.) 



