INTRODUCTION 203 



cup-like structure usually from a few millimeters up to several centimeters 

 in diameter. The texture is usually fleshy, fragile to tough, sometimes 

 leathery, and the color from pale brown to black, sometimes red, yellow, 

 or other colors, or even colorless. The upper surface constitutes the 

 hymenium, a layer of elongated cells standing at right angles to the sur- 

 face like a palisade. It consists of asci intermingled with supporting and 

 protective cells or hyphae, the paraphyses. Immediately below the 

 hymenium is a layer, thin or fairly thick, the hypothecium, consisting 

 mainly of light colored hyphae running parallel to the surface of the 

 hymenium and from which the asci and paraphyses arise. Often sharply 

 contrasted with the hypothecium but sometimes grading into it is the 

 excipulum which makes up the larger part of the basal portion of the 

 apothecium. Its tissue may be pseudoparenchymatous or may be formed 

 by interwoven hyphae. The outer (lower) surface may be filamentous or 

 may resemble an epidermis. Varying from this type we may find apothecia 

 borne on stipes (as in Sclerotinia) or the hymenium may be convex (as 

 in Pyronema) . In some cases the body of the apothecium is bent back 

 along the stipe so as to form a clavate structure with the upper portion 

 covered by an external hymenium {Geoglossum and Morchella) . In other 

 cases the apothecium is subterranean and variously folded internally to 

 form passages and chambers lined by the hymenium (various Tuberales) . 

 The apothecium proper is the product of the growth of the hyphae 

 adjacent to the ascogone, when this organ is present. It may develop 

 upon, underneath or within a more or less fleshy stroma or the stroma 

 may be entirely absent (most Pezizaceae). Corner (1929-1931) has made 

 a detailed study of the mode of growth and development of various types 

 of apothecia and concludes that their structure indicates relationship 

 to algal ancestors, possibly a group ancestral to the present Florideae. 

 (Fig. 68.) 



The typical perithecium is small, usually less than a millimeter in 

 diameter, and more or less spherical in shape. It is more often dark- 

 colored and somewhat hard and brittle, though not always so. Thus in 

 the forms customarily included in the order Hypocreales, the perithecium 

 may be bright-colored and fleshy or leathery. Usually, but not always, 

 there is an apical opening, the ostiole, through which the ascospores 

 eventually escape. It may be a simple opening or may have a low lip or 

 be drawn out to a long slender neck. As limited by Nannfeldt (1932) the 

 true perithecium is lined over the whole inner surface or only in its basal 

 portion by a hymenium composed of thin-walled asci (sometimes thick- 

 ened at the apex) intermingled with true paraphyses and with periphyses 

 in the ostiolar region. Julian Miller (1928) has shown that the true wall 

 of the perithecium lies within a stromatic structure which may form 

 simply a thin, darker-colored external layer or may form a massive struc- 



