130 



PLANT MORPHOLOGY 



It bears well-developed sex organs. The female organ resembles the 

 procarp of Nemalion. It consists of a globular, multinucleate basal por- 

 tion, the ascogonium, and an elongated curved cell, the trichogyne, arising 

 from its upper end (Fig. 105.1). The antheridium, which is terminal, 

 club-shaped, and multinucleate, arises from an adjacent hypha. It comes 

 in contact with the tip of the trichogyne, whose nuclei degenerate, and 

 discharges its contents into it. The wall at the base of the trichogyne 



A B 



Fig. 105. Pyronema conftuens. A, ascogonium and trichogyne with antheridium in con- 

 tact with its tip and discharging nuclei into it. Antheridium is curved around trichogyne 

 and appears in section to be cut in two. B, somewhat diagrammatic section of a young 

 ascocarp, involving two ascogonia from which ascogenous hyphae and paraphyses have 

 arisen. Asci are shown in various stages of development. (After Harper.) 



disappears and the male nuclei migrate into the ascogonium, where multi- 

 nucleate pairing of male and female nuclei occurs. The nuclei do not 

 fuse, however, until an ascus is formed. 



Following fertilization, the ascogonium is cut off from the trichogyne 

 by a new wall and branching ascogenous hyphae arise from it (Fig. 1055). 

 These give rise to asci. Sterile hyphae (paraphyses) grow up from the 

 mycelium and intermingle with the asci, the entire group of fertile and 

 sterile hyphae becoming surrounded by a fleshy ascocarp. Ordinarily 

 several sets of sex organs enter into the formation of a single ascocarp. 

 The ascocarp of Pyronema is disk-shaped, red or yellow, and only 2 or 3 

 mm. in diameter. The asci and paraphyses form a definite layer, the 

 hymenium, that covers its upper surface. A broadly open ascocarp is 

 called an apothecium, a type of fruiting body that is characteristic of the 

 Pezizales. 



The origin of the asci is somewhat complex (Fig. 106). The paired 



