A Botanical and Economic Study. 91 



matter how favorable the other conditions. 1 With the varieties 

 grown in the United States, in ordinary culture, an elevation 

 of over 2000 feet shows the yield of maize to be very small 

 indeed. 2 



Elevation and Yield. 



500 to 1000 feet, 54 per cent, total yield. 

 500 to 1500 " 82 

 Above 1500 " 4.4 " 



This was not the case, however, with maize grown in 

 Mexico and Peru. Humboldt" mentions that "vast maize 

 fields are to be found on the plateau of Mexico at a height of 

 8680 feet, and in Peru, on the road between Lima and Pasco, 

 maize is cultivated as high as 12,000 feet (3824 m.)." Sim- 

 monds 4 states that it is raised in tropical countries at a height 

 of 9000 feet and more. 



Professor Duges sent, in 1888, to the Cambridge Botanical 

 Garden, Boston, several maize plants, which he collected at 

 Moro Leon, otherwise Congregacion, near Uriangato, four 

 Mexican leagues north of Lake Cuitzco, and, therefore, near 

 the boundary line between the States of Guanajuato and 

 Michoacan. Grains from the Mexican plants sowed in 1892 

 in Philadelphia, in the middle of May, perished for some 

 reason, but one developed into a specimen about five feet high, 

 which showed great hardiness, the growing period extending 

 to the fourteenth of November, when the stalk was cut. The 

 plant stood well the frosty days, and a snowstorm which 

 came before it was cut did little harm. The exceptionally 

 dry autumn suited the plant well, which throve better in the 



1 Darwin, Variation of Animals and Plants under Domestication, i, 322. 



- The absence of large areas of tillable land in the United States at the elevation of 

 2000 feet explains this distribution of crops in altitude, for Dr. William P. Wilson informs 

 me that some of the largest and most luxuriant crops of corn he ever saw were raised on 

 the mountains of North Carolina at an elevation of over 4000 feet. This exception to the 

 above statement enforces the view hereafter expressed as to the elevation at which the 

 wild corn grew. Broadly speaking, high vertical thermometric zones correspond to high 

 latitudes, low vertical zones to low latitudes ; the elevation (4000 feet) in North Carolina, 

 therefore, represents a much higher altitude in the tropics. 



:i Meyen, Geography of Plants, Ray Soc, 1846, 304. 



4 Simmonds, Tropical Agriculture, 1877. 



