468 CLASS BASIDIOMTCETEAE 



The colors may be white or shades of gray or bright-colored or almost 

 black. 



The mycelium in perhaps the majority of the Hymenomycetes shows 

 clamp connections. These may be found generally in the vegetative 

 mycelium as well as in the spore fruit or may be lacking in the latter or in 

 both. In abnormal forms whose mycelium is of the monocaryon type only, 

 clamp connections are lacking, but their absence in any given species 

 does not necessarily indicate such an abnormal type. Cytological study is 

 required to determine whether hyphae without clamp connections are 

 monocaryotic or dicaryotic. 



Tischler (1927) and others who have made cytological studies in the 

 Higher Fungi report that for the Hymenomycetes as well as most other 

 Basidiomycetes the haploid number of chromosomes is mostly two, 

 although in a number of species it may be four, six or eight. 



The basidiospores are various in shape; globose to ellipsoidal to ovoid 

 and in some genera angular or knobbed (Rhodophyllus) . They are rarely 

 symmetrical in more than one plane, that which passes through the spore, 

 the sterigma and the center of the apex of the basidium. Apparently 

 almost without exception they are perched in a slightly oblique manner 

 on the tips of the sterigmata from which they are expelled with violence. 

 They are nonseptate but in Exobasidium may become transversely 

 septate before germinating or even before being discharged. Normally 

 they germinate by a germ tube which may arise from any point on the 

 spore wall or only from a specially located germ pore. They vary in color 

 from hyaline, pink, red, yellow, ochre, ferruginous, to purple and black. 



Conidia are produced in this group but in a rather limited number of 

 species scattered throughout the two orders. They occur on various types 

 of conidiophores. When produced internally in the spore fruit in a cushion- 

 shaped or spherical structure they are usually placed in the "form genus" 

 Ceriomyces but when formed externally may be called Paramyces. 

 Chlamydospores are produced abundantly in Nyctalis asierophora Fr. 

 and elsewhere. Oehm (1937) concludes that there are no true conidia in the 

 Hymenomycetes but that they are all to be considered as various forms of 

 chlamydospores. 



Besides the foregoing the monocaryon stage of the mycelium of very 

 many species produces oidia which appear to be capable of functioning as 

 sexual cells (see Chapter 12), but which in some cases serve as conidia. 

 More rarely they are produced as two-celled oidia on dicaryon mycelium 

 but usually the two cells then fall apart and function like the uninucleate 

 oidia from the monocaryon mycelium. This was reported for Plioliota 

 aurivella (Fr.) Quelet by Vandendries and Martens (1932). 



In the author's earlier book all of the Hymenomycetes were in- 

 cluded in one order, the Agaricales, but the modern tendency is toward 



