Suggestions for Lichen Studies. 



25 7 



these species, and of ocean water on other lichens from a more in- 

 land habitat? Does anv one know? 



The influence of moisture on a given lichen is abundantly 

 illustrated in a number of cases, but by none better than Rama- 

 Una reticulata. Where this plant grows on foggy coasts the 

 thallus is excessively subdivided, with perforated expansions 

 but a fraction of a milimeter in breadth; while in the dry, inter- 

 ior lowlands the unperforated expansions may reach a breadth 

 of more than 40 mm., the whole plant being markedly coarse in 

 habit. In fact the variation in habit of this plant is a pretty 

 good indication of the fog channels and rain-laden wind currents 

 of the Coast Range mountains. 



But what would be the result of the acclimatization of a 

 lichen? So far as the writer knows, this has never been at- 

 tempted. Yet it w T ould seem that a form like Ramalina reti- 

 culata might readily be "planted" on the limbs of trees on the 

 coast of Florida or Louisiana. It might live and in time vie 

 with Tillandsia usneoides, or — it might not. But it would be 

 interesting to transplant a number of lichens and see what 

 changes, if any, the new environment w r ould effect. For ex- 

 ample, it might throw some light on why a given species should 

 be so much more luxuriant in one region than another. R. H. 

 Howe states (Bull. Toir. Bot. Club, XXXVI, 315; 1909) that the 

 "great luxuriance of Pacific Coast specimens (is) due evidently 

 to abundant moisture." This is not so evident to those of us 

 who live at present on the Pacific Coast and who are familiar 

 with the flora of all parts of the United States; it may be true of 

 some species perhaps, but it is certainly not true of the Usneas 

 of which he is speaking. One could hardly be so sure of abund- 

 ant moisture when six or seven months often pass without rain, 

 the annual precipitation of 15 to 40 inches coming during the 

 winter months. It is true that there are some summer fogs, but 

 they lack much of supplying adequate moisture, though of course 

 they have an appreciable effect upon vegetation. The aridity of 

 California in general is shown by her xerophytic forests and 

 impenetrable gnarled chaparral, and by the great number of 

 endemic xerophytic lichens, such as Heppias and Acarosporas. 



