Effect of Moisture on the Growth of Usneas. 69 



"The excessive length of species of Usnea in some regions is 

 directly due to having never been disturbed; for example, Usnea 

 longissima reaches a length of six or seven meters in the forests 

 of Baron Rothschild's estate in Hungary, where an axe has not 

 been allowed for more than one hundred and fifty years; here 

 in California it is ten or twelve feet long only in the redwood 

 forest not yet visited by the lumberman, where it grows upon 

 trees which are 500 to 1,500 years old. The author also believes 

 that the greater size of many California lichens may be due to 

 the prolonged growing season (of seasonal and continuous rains), 

 though of course this can only be settled by careful measure- 

 ments and extended series of observations." 



I do not desire to enter into any controversy with Mr. Herre, 

 nor to question that his knowledge of the climatic conditions of 

 the Pacific Coast is greater than mine, for I have never been 

 west of Wyoming; but I do wish to state the facts gathered from 

 reliable sources, and from Mr. Herre's own works on which I 

 partially based my statement, and the import of which he has 

 evidently forgotten. 



In the first place the "Pacific coast", as I used the term, 

 extends from the coast of Southern California to Alaska; the 

 rainfall figures which he gives, "15 to 40 inches" per annum, 

 referred, I take it, to his own state of California, inland as well as 

 coast stations figuring in the average. The annual average rain- 

 fall of the Pacific coast is about 65 to 70 inches, and climatic 

 "moisture" including humidity (84%), ocean fogs (.14 inches 

 per day for 250 days — 35 inches rainfall approximately), and 

 rainfall (21.71 mean, 34 max., 12.44 monthly max. Dec.) for the 

 region of Alpine Creek Canyon, San Mateo Co., Cal., where the 

 local eflFect on Usnea plicata (L.) Web. {Us. Calif ornica Herre?) * 

 was one of the instances I had in mind. In the latter place it 

 averages yearly the equivalent in other words of approximately 

 55 to 60 inches rainfall, f 



In Mr. Herre's paper (Bot. Gaz. 38:218-219. 1904) on 

 the growth of the closely allied Ramalina recticulata Kremp., 

 made, I take it, near Stanford University or in the Santa Cruz 

 mountains (San Mateo Co.), the only localities cited, he writes: 



*U s. barbata var. ceratina Schaer. of Tuckennan, a contingent phase of plicata. 

 t-McAdie, CUmatology of Cal. 1903. 



