438 



BOTANY OF THE LIVING PLANT 



The fruit-bodies are very complex in some of tlie larger saprophytic 

 Ascomycetes. An extreme case is seen hi the edible Morel [Morchella 

 esculentd), in which the external hyraenial surface is convoluted so 

 as to accommodate a vast number of asci. It is possible to refer this 

 to an elaboration of the Discomycetous type, as it is seen m Peziza 

 (hig. 370). But in the Truffle {Tuber) the equally numerous asci are 

 borne internally, hi the large underground tuberous fruit (Fig. 371). 



ASCO-LICHENES 



There is a series of Ascomycetous Fungi which live in symbiotic 

 relation with Algae, and thus constitute compound bodies which are 

 called Lichens. The physio- 

 logical relation of the two 

 distinct organisms is not unlike 

 that of the Fungus and Host- 

 plant in mycorhiza, but there is 

 here no intra-cellular digestion 



Mc. 372. 

 A=^Xiuiiliona {Fanmhaj panciina, the coiiiiiiou foliaLCOUb- y(. lli.)\v Lit^lien. 

 B = Clad(ynia rangifera, a fruticose Lichen- Both hc-ar ascus-truits, and are shown 

 natural size, (.\fter Strasburger.) 



(Chapter XL). The Lichens are verv various in form. In simple 

 cases they may be filamentous, as m Ephebe, which is like a filamentous 

 Alga with a fungus growing in its mucilaginous walls. Some appear 

 as flat gelatinous thalli, readilv swelling with water, as in Colleina, 

 wliieh is based upon the gelatinous Alga, A'Osloc. Others are more firm 

 in texture, and form variouslv flattened thalli, more or less closely 

 attached to the substratum of rocks, roofs, or tree-trunks, etc. Others 

 again arc erect or pendulous, and often liranchetk rising freelv from 

 their Ijase of attachment. In texture they are liriltlc \\hcn drv, but 

 more or less leathery when moist, and tliev wiry greatly in colour 

 from grey to more vivirl yehow, or c\-en red. Tliev are curiously 



