216 PHYLUM VII. CARPOMYCETEAE 
tion and ample opportunity for growing. There is thus 
an association between these plants which is mutually 
beneficial (symbiosis) ; the fungus lives parasitically upon 
the green algae, to which in return it furnishes 
shelter and moisture. 
344. Among the Disk Lichens one of the 
simplest is the Thread Lichen (Epbebe) found 
on wet rocks. In it the fungus filaments 
Fie. 97. grow over and around the cells of Scytonema 
Ephebe < 
pamattie a. OF Stigonema filaments. ; bd 
345. Some other Disk Lichens are parasitic 
upon Nostoc colonies, as in the Jelly Lichens (Collema, 
Leptogium), while for the greater part they are parasitic 
on species of Protococcus, as is the case with the great 
majority of common lichens—Cladonia, Theloschistes, 
Physcia, Parmelia, Ramalina, Usnea, etc. 
Tue Cup-runc1 (ORDER PEZIZALES) 
346. The common Cup-fungus of the woods is a typical 
representative of this order. The familiar cup- or saucer- 
shaped growthisin reality the spore-fruit (“apothecium”), 
while the plant itself is out of sight. The plant consists 
of whitish, septate filaments which grow on or in the 
ground or in rotten wood, drawing their nourishment from 
decaying vegetable matter. These plants are therefore 
saprophytes. Some Cup-fungi, however, are known 
to be parasites. 
347. But little is known as to the asexual reproduction 
of the Cup-fungi, but in some species conidia have been 
observed. 
348. Thesexual organs of Pyronema (“‘Peziza’’) are pro- 
duced by the swelling up of the ends of certain of the fila- 
ments of the plant into globular or ovoid cells, the oogones, 
each having a projection (trichogyne). From below each 
