280 University of California Publications in Botany [Vol. 6 



is still destitute of asci or spores, whicli makes the identification of species im- 

 possible. So far as I have seen, the spore does not arrive at maturity until 

 April; much, however, depends upon the weather. 



Professor Gardner's experience in regard to seasons differs some- 

 what from the preceding, for he has collected various species of Tuber 

 which were fully developed in the early part of December. As Dr. 

 Harkness has stated, hoAvever, much depends upon the weather, and 

 the years of early Tubers correspond to those in which early and fre- 

 quent rains are followed by warm sunshine. 



The trees and shrubs which Dr. Harkness cites as associates of 

 ascomycetous forms are: Quercus, Pinus, Abies, Sequoia, Libocedrus, 

 Ceanotlnis, Eucalyptus, Arctostapliylos, and Heteromeles. Professor 

 Gardner adds Arbutus and Salix to the list. In few cases was a fungus 

 discovered always to be associated with the same kind of tree or shrub, 

 some species even being found under various conifers as well as de- 

 ciduous trees. 



Many species, according to Professor Gardner, grow only under 

 leaves, while some are truly hypogaeous and occur sometimes several 

 inches under ground. The soil may be light and porous, or may be 

 of heavy clay. The latter is evidently preferred by Tuber candidum, 

 which is often found buried two or three inches deep. It is reported 

 also, however, as growing in both leaf -mold and sand. 



IV. ECONOMIC IMPORTANCE 



Dr. Harkness states (1899, p. 244) : "All of the Californian species 

 are . . edible, and no doubt would be greatly esteemed as a luxury 

 were it not for the fact that they are so rare as to practically prohibit 

 their use as food." On the same page he refers to a species which a 

 number of years ago was discovered in large quantities near Marys- 

 ville and Sacramento. It was freely eaten and considered a great 

 delicacy ; and from its large size and its effect upon the surface of 

 the ground above it, Dr. Harkness, who knew it only by report, be- 

 lieved it to be a species of Terfezia, a genus well known in Southern 

 Europe and Western Asia for its edible qualities. Unfortunately, no 

 further notes have been made, and whether or not a Terfezia exists in 

 California is still unknown. 



Professor Gardner has found Tuber candidum, T. calif or nicum, 

 and Geopora Harknessii in comparative abundance, but no particular 



