398 



BOTANY 



PART n 



Order 5. Tuberaceae (Truffles) ("^) 



The Tuberaceae or Truffle Fungi are saprophytic Ascoraycetes uhose mycelium 

 occurs in humus soil, particuUxrly in woods. The ascus fructifications familiar 

 under the name of truffles are underground tuberous bodies, consisting of a 



r^^AN^ 



Fir,. 329. — Tnher rufum. 1, A fnictilieation in vertical section (x 5) ; «, tlie cortex ; d, air-containing 

 . tissue ; c, dark veins of compact liyphae ; h, ascogenous tissne : 2, a portion of the liynienium 

 (x 400). (Alter TuLASNE, from v. Tavel.) 



thick, investing layer, with passages opening to the exterior; the walls of tiiese are 

 lined with the hynienium conipend of club-shaped asci (Fig. 329). Tlie asci 

 contain only a small number of spores ; in the case of the true truffles {Tuber) they 

 are usually only four in number, and generally have a spinous or reticulately 



