548 



CLASS BASIDIOMYCETEAE 



early and the spores are in some species enveloped in a sheath of nurse 

 hyphae till maturity when everything disappears except the spores and a 

 few capillitial threads. The spore fruit may crack open stellately or may 

 be opened by attacks of insects or rodents. Pisolithus does not have so 

 thick a peridium and the tramal sheets split in such a manner that the 

 basidium-producing areas form numerous ellipsoid or round "peridioles" 

 retained within the peridium. Finally these fall apart into a powdery spore 

 mass. The capillitial threads are few. The basidia bear two to six almost 

 sessile, rounded spores. There is no special means of dehiscence provided 

 in this genus. 



Order Nidulariales. In this order the spore fruits are external, not 

 subterranean. They have a thin or thick peridium and the gleba contains 

 several to innumerable hymenial cavities, apparently formed in the lacu- 

 nar manner, each lined internally by a layer of basidia. The tramal tissue 

 in Family Nidulariaceae forms a firm several-layered wall around each 

 cavity with its contained spores and these hard-walled bodies, called 

 "peridioles" lie in the bottom of the cup formed by the dissolution of the 

 top peridium of the spore fruit and of the tissues surrounding the peridi- 

 oles. In Family Arachniaceae placed in this order by Fischer, the perid- 

 ioles are innumerable and the tramal wall of each is thin and fragile. 



Family Nidulariaceae (Bird's Nest Fungi). Several peridioles, 

 over 20 in Nidularia, are formed in each spore fruit. At first connected in 

 a continuous gleba the peridioles early become separated from each other 

 and lie free in the cavity of the spore fruit or are connected to the peridium 

 by long slender strands, the "funiculi." The principal genera are Cruci- 

 bulum, Cyathus, and Nidularia. The spore fruits are several millimeters 



Fig. 180. Nidulariales, Family Nidulariaceae. Cyathus striatus Pers. Three 

 opened fruit bodies showing peridioles and one unopened spore fruit. (Courtesy, 

 F. C. Strong.) 



