ORDER PROTOGASTRALES 535 



Tulostomataceae and possibly the Podaxaceae. Some genera usually 

 assigned to the Sclerodermatales probably belong in this series. The gleba 

 breaks down by autodigestion and leaves the spores and sometimes also 

 the basidia and the hyphae making up the capillitium, as a dry powdery 

 mass, spore distribution taking place by air currents. A fourth tendency 

 shown by the Sphaerobolaceae, Nidulariaceae and the genus Pisoliihus, in 

 the Sclerodermataceae, is the formation of firmer walls around definite 

 regions of the gleba so that these are distributed as units, either by 

 mechanical means or currents of water or by violent expulsion from the 

 fruit body. These probably do not form a connected series but represent 

 separate evolutionary changes from both the Hymenogastrales and the 

 Sclerodermatales. 



The orders tentatively recognized here are Protogastrales, Hymeno- 

 gastrales, Sclerodermatales, (possibly better distributed among other 

 orders), Lycoperdales, Nidulariales, Sphaerobolales, Phallales. The late 

 Sanford M. Zeller (1948, 1949) recognized 9 orders and 32 families instead 

 of the 7 orders and considerably fewer families recognized in this work. 

 Until much more intensive study has been given to the ontogeny of the 

 sporocarps of the G aster omyceteae any arrangement must be considered 

 to be more or less tentative. 



Order Protogastrales. In this order the minute spore fruits have but a 

 single hymenial cavity. The hymenium consists of basidia without cys- 

 tidia, and the basidiospores are light-colored and smooth. Protogaster was 

 described by Zeller (1934). It is a minute fungus growing on the roots of 

 plants in Maine and has been found but once and then only in the mature 

 stages. It consists of a nearly spherical spore fruit, less than a millimeter 

 in diameter. It contains a single large cavity lined by basidia bearing 



B 



^ 



^^IX I 



'% ^^ 



^^:^ J^l^""^ 



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Fig. 172. Protogastrales. (A) Family Protogastraceae. Protogaster rhizophilus 

 Thaxt.; diagrammatic median section of spore fruit. (B-D) Family Hemigastraceae. 

 Hemigaster candidus Juel; three stages in the pseudoangiocarpic development of the 

 spore fruit. (A, courtesy, Zeller: Ann. Missouri Botan. Garden, 21(2):231-240. B-D, 

 from Comparative Morphology of Fungi by Gaumann and Dodge, New York, 

 McGraw-Hill Book Co., Inc.) 



