CONTRIBUTIONS TO WESTERN BOTANY NO. 15 



*■ 



Victoria mountains can apply only to an insignificant sub rant^encar 



term 



area north of La Paz. 



liui uiis aoes nor reacn nign enou 

 special significance, compared with the p^reat La^runa ai 



I believe that it i.<; aht;ohitplv 



with 



necessary 



credit to the evidence obtained 



of each zonal guide ?(> 



guide becomes 



NELSON AND LIFE ZONES 



4 



NeLson, head of the U. S. Biol. Survey, in his memoir of the VVmefi- 

 can Academy on Lower California, tries to perpetuate Merriam's monu- 

 mental blunder in life zones by keeping up ^erriani's system of senaraS 

 ing the Temperate from the Tropical, calling the life of the lower part- of 

 the peninsula Tropical and drawing the zonal limits at least SCO niilcs 

 too far south. In addition in his map he makes another serious 'blunder 

 in mapping the life zones of southern California where he reprr.^ents the 

 entire littoral flora and interior flora up to the bases of the Sierras -li- 

 ''Up'per Sonoran," when in fact it is Merriam's Lower Sonoran, which 'in 

 turn is truly Tropical, as shown by me in Contributions No. 13. 'G.'nj- 

 nell also has made much the same blunder in his discur-sion of the zonal 

 limits of northern Lower California. The reason for this is that nriHv>- 

 person has taken into account the annual temperature of the 'regions dealt 

 v/ith, which is in excess of 60 degrees Fah. Most of the botanist;" of 

 f-<5uthem California have fallen into much the same error, all becaii'-e 

 they did not find a suitable zonal plant to dieck up on "the^ western si^'e 

 of the mountains, where the annual humidity was so high. On the fa?^- 

 ern side of the mountains, the desert side, the Larra is a conspicuous 

 zonal plant, serving w^ell to separate the Lower Sonoran of Merri^m f o^^i 

 the Upper Sonoran of Merriam, wbd^e characteristic plant is Junirenis 

 Utahensis. Now on the western side of the mountains, because 6i flic 

 high humidity the Larrea is not found, but its place is taken by Adeno.-- 

 toma fasciulatum, which is an admirable zonal plant and enables -the 

 acute observer to draw the limits of the zone nicely throughout the entire 

 area as far north as Eureka, California, and enables one to correlate the 

 other plants in their proper zones. This reveals the fact that the flo-a of 

 the plains of California from San Diego to Eureka, California, 'including 

 the great inter valleys, is Tropical, that is, Lower Sonoran, up to an 

 elevation of 5,500 feet in the San Bernardino and San Jacinto mounta'ins, 

 and about to Colfax east of Sacramento. Hall and others* have tried to 

 dodge the matter by devoting much to what they call the chapparal 'belt, 

 v/hich is nothing but a drainage piroposition, having nothing to "do with 

 life zones. 



I have recently returned from a long trip throughout 'the region cov- 

 ered by Nelson, and can say with precision that "if the Xarrea arid "^Fou- 

 quieria are not Tropical plants then there is no Tropical- 'Aboiit^lhat I 

 shall treat more in detail elsewhere. 



