WAX PALMS— BOMHARD 321 



"World varieties of the date palm {Phoenix dactylifera) in the south- 

 western United States in advance of their being tried oiit,^^ informs 

 me that probably no other region in the North Temperate Zone so 

 nearly parallels the cool climate of the Cordilleras as does this 

 Pacific coastal strip of our country. 



Fortunately the climate of the Cordilleras of Venezuela, Colom- 

 bia, and Ecuador — the very regions where the most beautiful wax 

 palms grow — has been especially studied by the well-known au- 

 thority on regional meteorology, Julius Hann. A comparison of 

 climatologic data from four locations in the Andes given by him 

 with equally authentic data for seven stations on the Pacific coast 

 thermal strip is set down in the table on the following page. 



A detailed discussion of the figures given in table 1 is beyond 

 the scope of this article. However, the only important disparity is 

 in the greater difference between the mean temperature of the hottest 

 and coldest months on the Pacific coast as compared with those of 

 the Andean stations. It should be recalled that wax palms are ac- 

 customed to endure, apparently without injury, temperatures only a 

 few degrees above the freezing point. According to Hann's rule, the 

 temperature of the "tierra templada" and "tierra fria" zones of the 

 Cordilleras from Venezuela to Ecuador decreases about 1° F. for 

 every 337.5 feet ascent; or, roughly, 3° F. for each 1,000 feet. Andre 

 recorded an early morning temperature of 2° C. (35.6° F.) at Las 

 Cruces in March; j'et March is one of the hottest months of the 

 Quindio region. The temperature at the upper limit of the Quindio 

 palm, higher up the mountain, would, by Hann's rule, have been only 

 one-sixth of a degree (0.164° C.) above freezing; at the Volcan 

 Chiles, where utile grows, it would have been —5.77° C. (21.6° F.) at 

 that time. On the Pacific coast from San Francisco to San Diego, 

 where there is almost no variation in altitude, the temperatures in- 

 crease, roughly, 1° F. for every 55 miles going south; or, in other 

 words, moving northward 165 miles along the Pacific coast of Cali- 

 fornia would correspond to an increase of 1,000 feet in altitude in the 

 Andes. 



The length of day varies but little between summer and winter 

 near the Equator but does vary decidedly at latitudes 30° to 47° north 

 of the Equator in California and Washington, where the summer 

 days are longer than in the Quindio Pass region. However, fre- 

 quent showers in Washington, almost daily dense fogs in San Fran- 

 cisco, and the "velo", or high fog, of San Diego all cut down the 

 hours of effective sunshine during the long summer days and tend 

 to obscure or even obliterate the difference in length of the summer 



^ Swingle, W. T., The date palm and Its utilization in the southwestern states. U. S. 

 Dept. Agr., Bur. Plant Indue. Bull. 53, 1904. 



