. A textbook of botany for colleges and universities ... Botany. 74 MORPHOLOGY "swollen hypha " represents the female sex organ, which by fertilization or not becomes the ascogonium. Applying these facts to Peziza and to the other Pezizales, it is probable that in them an ascogonium related to a sexual act is present either actually or historically; and that the nuclear fusion, which represents the essential feature of fertihzation, is likely to have persisted in the life history even though apparent sex organs may have disappeared. (e) Tuberales These are the truffles, whose myceliu
. A textbook of botany for colleges and universities ... Botany. 74 MORPHOLOGY "swollen hypha " represents the female sex organ, which by fertilization or not becomes the ascogonium. Applying these facts to Peziza and to the other Pezizales, it is probable that in them an ascogonium related to a sexual act is present either actually or historically; and that the nuclear fusion, which represents the essential feature of fertihzation, is likely to have persisted in the life history even though apparent sex organs may have disappeared. (e) Tuberales These are the truffles, whose mycelium is entirely subterranean in humous soil. A remarkable subterranean, tuber-like, fleshy ascocarp is produced, which is the edible trufile. The ascocarp completely incloses the asci, and this closed type is often designated a cleistothecium, to distinguish it from the open ascocarps (apothe- cia). The cleistothecium of Tuberales consists of a fleshy cortex and a central ascus-forming region. In maturing, the interior sterile tissue and the asci disappear, leaving the ascospores free within the cortex. Very little is known of the life history of the Tuberales. It has been suggested that the mycelium may be that of some root fungus (mycorhiza), for in France and Italy, the chief market sources of the truffles of commerce, they are found constantly under oak trees. (f) Plectascales This group comprises saprophytes with an extensive mycelium, closed ascocarps (cleistothecia) of peculiar structure, and abundant produc- tion of conidia. The best-known repre- sentatives are the blue and green molds: Aspergillus (Eurotinm), the herbarium mold, also on bread, preserves, etc.; and Penicillium, the common blue mold on bread, etc. From the mycelia the sporophores (conidiophores) arise in profusion, and their terminal branches by abstriction produce rows of conidia (fig- 179)- The sex organs are represented by two short, spirally intertwined filaments. Fig. 179.—Pen/cWmot; branches Their
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