CALOSTOMATACEAE 



Fruit body hypogean or partly so until maturity, attached by obvious basal strands; 

 with or without a stalk. Peridium highly specialized and formed of several layers. 

 Gleba without cavities or organized hymenium, separated into small blocks by delicate 

 tramal plates or strands. Capillitium or its rudiments arising from the whole inner 

 surface of the inner peridium. Basidia irregularly arranged, stout, club-shaped, 

 bearing several, usually more than 4, spores irregularly scattered and sessile around its 

 surface. Spore powder dry and escaping by an apical mouth. 



ASTRAEUS Morgan 



This genus, formerly included in Geaster and of the same general appearance, was 

 established by Morgan on the following essential differences: no open chambers and 

 therefore no organized hymenium ; threads of the capillitium long, much branched and 

 interwoven, scarcely different from the elemental hyphae of the peridium and con- 

 tinuous with them, in these respects agreeing with Tylostomd; columella entirely lacking ; 

 spores much larger than in any Geaster. The hygroscopic character of the rays is very 

 marked, as is their hard and woody texture when dry. 



There is but one species known. 



Morgan and Burnap call attention to the apparent relationship of this genus to 

 Tylostoma and Colostoma and Fischer puts it in the Calostomataceae, in which he has 

 been followed by others. We are following this precedent, although it is far from clear 

 that it belongs here rather than in the Tylostomataceae. It seems to us that it would 

 be better to establish another family for it, as its presence in any recognized one makes 

 the definition of that family awkward and unsatisfactory. Fischer's definition of the 

 Calostomataceae includes the statement that the capillitium is well developed. This 

 is not true of Colostoma, in which the rudimentary "capillitium" disappears entirely before 

 maturity (see p. 189). Relationship to Colostoma is shown mainly in the organiza- 

 tion of the gleba into stuffed areas and the stout basidia with a varying number of 

 scattered, partly lateral spores, and the highly complex organization of the coats. Its 

 relationship to Tylostoma is indicated by the absence of open chambers, the basidia and 

 spore characters, though the latter has only 4 spores, and by the highly developed 

 capillitium, which arises from the entire inner surface of the peridium. 



Astraeus hygrometricus (Pers.) Morg. 

 Geaster hygrometricus Pers. 

 Geastrum fibrillosum Schw. 

 Geaster slellatus Scop. 

 Astraeus slellatus (Scop.) Fisch. 



Plates 31, 77, 115 and 117 



Plants of small to medium size, growing in colonies just beneath the soil or partially 

 exposed, arising from a group of black, hairlike, basal rhizomorphs. Outer peridium 



185 



