310 



Mycologia 



persion of the spore is secured by the slugs that infest the plants 

 and also by the rodents that sometimes use them for food. The 

 plants have no odor, but are rather nutty of flavor and are abun- 

 dant enough to be useful for food. Specimens this year have 

 measured over three centimeters, which is larger than described 

 for the species. 



It has been found abundantly in one vineyard near the Guada- 

 loupe Mines, and at Alma I found some fine large plants among 

 the grass roots in a pasture adjacent to live oaks. 



Tuber tignarium, or what has passed for that species, as col- 

 lected in this district is perhaps the most interesting form so far 

 collected. Described originally as Terfeziopsis lignaria by Dr. 

 Harkness, the collector, it has been recently placed in the genus 

 Tuber by Dr. Gilkey on a very careful study of the original collec- 

 tion. In its general appearance it is very close to T. candidwm. 

 The plants found here differ somewhat from the description of 

 the type, although they have the typical spores with the recurved 

 spines. During the past season it has proven more abundant than 

 T. candidum and is to be found over a wide area and over a long 

 season. 



Considering its previous appearance in but one collection its 

 occurrence here is of exceptional interest. In the spring of 19 17 

 a small dark brown tuber, always immature, appeared in collections 

 made all through this district. Plants occurred in all kinds of 

 ground and under many trees, but generally in association with the 

 oaks. Plants are uniformly a dark brown with areas of a lighter 

 color where the venae externae open to the surface. The plants 

 appeared in abundance on the warm upper slopes of the hills, 

 where the growth is more open and the soil moist and light. 

 Plants are found close to the surface, but usually down to a depth 

 of three or four inches. 



A long drought occurred and tubers of all kinds were very 

 scarce until the winter of 191 8-19. This drought was broken by 

 a prolonged storm early in September of 191 8. Over twelve 

 inches of rain fell in three days at the Guadaloupe Mines. Fol- 

 lowing this rain there came a warm, humid spell lasting over 

 a month, which was ideal for the growth of fungi. On the 



