34 HUMPHREY 



At any rate, it is evident that under conditions prevailing in 

 this part of California a second crop of antheridia appears before 

 the close of a single growing season, and in the case oi J^ossom- 

 bronia at least, when the supply of moisture is maintained, ferti- 

 lization and ultimate development of the sporophyte proceed 

 regularly, the spores ripening three or four months earlier than 

 those of the winter crop. It is probable that the second growth 

 of antheridia and archegonia begin to develop at least a month 

 before the close of the rainy season, and this fact is of particu- 

 lar importance to the plant as it insures the maturity of the 

 sporophytic generation well within the rainy season. 



Certain of our liverworts show a tendency to develop tubers 

 or other structures enabling them to resist drought. For ex- 

 ample, in the southern part of the State, GeothalliLS tiiherosus is 

 a form bearing well-marked tubers, while in our own locality 

 Fossomhroriia develops tuber-like thickenings of the stem, and 

 well-defined tubers are to be found in the case of Anthoceros 

 ■phymaiodes. All the plants employed in this study showed the 

 presence of scales or hairs which in some instances secrete 

 mucilage ; these along with the mucilage cells within the thallus 

 are structures undoubtedly serving as water-storage organs. 



According to Howe,^ aside from Ant/iocerosphymatodes, tuber- 

 ous structures are not uncommon among plants of A.fearsom\ 

 both species growing ordinarily in exposed places. In other 

 parts of the world, hepaticae bearing tubers have been found. 

 For example GoebeP describes two species of Anthoceros^ A. 

 argentinus and A. dichotomus and a species of Fossomhronia^ 

 F. tuberifera, common in certain parts of Chili. He regards 

 the organ in the last named species a true tuber not unlike the 

 same structure developed by our Anthoceros phymatodes, but 

 considers the tubers oi A. argentinus and A. dichotomus as trans- 

 formed branches of the thallus, the ends of which, have become 

 swollen and filled with reserve food products, very similar to 

 what prevails in our common species A. pearsoni. Goebel' 

 also reports certain species of Riccia as developing tubers, 



^ Loc. cit., p. 184. 

 ^ Loc. cit., p. 293. 

 ^ Loc. cit., p. 70. 



