244 



COMPARATIVE MORPHOLOGY OF FUNGI 



tened (Fig. 160); its upper side is covered by a solid rind while the lower 

 only form the perithecia. In this form, the Hypocreales have a type of 

 fructification which one would, without study, consider polyporaceous. 

 In Ascopolyporus, the imperfect forms are Fusaria, while in Mycomalus 

 they are reminiscent of Ustilaginoidea. 



The second series of the Scolecosporeae, Epichloe-Claviceps, is epi- 

 phytic or parasitic on Gramineae. Epichloe possesses flat undifferentiated 

 stromata which correspond to the lower species of Hypocrella. E. 

 typhina forms sheaths around the stems of the meadow grasses; the young 

 stromata form enormous numbers of small, hyaline conidia; later they 

 develop the golden-yellow perithecia, at first singly, later in a continuous 

 layer. E. bambusae, in the Sunda Archipelago, infects several species of 

 bamboo, Gigantochloa apus, Dendrocalamus flagellifer and Bambusa 

 Blumeana, and stimulates them to the formation of long, pendant witches' 



brooms. Unlike E. typhina it possesses no 

 imperfect forms. The ascogonium consists of 

 a row of two to five cells, each containing three 

 to seven nuclei. The wall between two cells 

 disappears and the nuclei pair. The details 

 of the process are not clear but the ascogenous 

 hyphae grow from these cells, eventually pro- 

 ducing asci as in Pyronema confluens (Gau- 

 mann, 1927). 



Fig. 160. — Ascopolyporus While in Epichloe typhina the fundaments 

 poiyporoides on bamboo. (Nat- f the perithecia are limited to irregularly 



ural size; after Moller, 1901.) . . . . . . ,. 



denned spots and, by the confluence of the 

 perithecia, develop into a homogenoeus stroma, in Ophiodotis, they are 

 retained to the maturity of the stroma; as in the higher species of Hypoc- 

 rella, Mycomalus and Ascopolyporus the upper surface of the stroma is 

 differentiated into fertile and sterile zones. 



The Brazilian Ophiodotis Henningsiana on Andropogon, forms black 

 stromata several centimeters long, resembling those of Epichloe. At the 

 time of perithecial formation the thin stroma thickens in spots, often as 

 much as fivefold, so that at maturity the fungus forms an uneven, verru- 

 cose stroma (Fig. 161, 2). On account of this dark color and the fragility 

 of the stromata, Ophiodotis is usually placed in the Sphaeriales; but its 

 transfer to the Hypocreales, where it doubtless belongs in the Epichloe- 

 Claviceps series, is desirable since many Xylariaceae are only slightly 

 harder than many species of Hypocrella. 



The South American 0. raphidospora keeps the perithecial thickening 

 within more definite limits. It appears on young, still rolled, bamboo 

 leaves in the form of black stripes several centimeters long and hinders the 

 unfolding. As in Epichloe Bambusae the plectenchyma completely fills 

 the spaces between the leaves and transforms them to pseudomorphs. 



