1921] Smiley: Flora of the Sierra Nevada of California 31 



warmest locality but this time the advantage comes at the height of 

 the growing season (August). All through the first half of the year 

 Tahoe is cold or cool: in Januarj-, February, and March, this lake 

 station is colder than Fordyce or even Summit, though the latter 

 place is 800 feet higher ; in earlj^ spring Tahoe becomes warmer than 

 these two stations, being, after Bridgeport, the warmest station, but 

 as soon as the snow-cover melts from about Summit its monthly mean 

 temperature rises and becomes greater than that of Tahoe till August, 

 when, as stated above, the vegetation at Talioe is the most favorably 

 situated as respects heat of any of the plant populations resident at 

 this series of mountain stations. In the fall and early wdnter Tahoe 

 is warmer than the high station of Tamarack and warmer than 

 Fordyce and Bridgeport. 



If the diagram be considered with regard to the relative climate 

 of Summit, it will be noted that at the beginning of the year and in 

 the fall and early winter Summit is the warmest station ; for seven 

 months in the twelve its mean temperature is the highest and, in the 

 most favorable part of the j^ear for growth, Summit is next to the most 

 favorable place. Its spring temperature clearly shows the chilling 

 effect produced b}'- melting; in March when the snow-cover attains 

 its maximum thickness (table 5) and before melting begins. Summit 

 is relatively warm but, with diminution in the snowfall combined with 

 the higher mean temperature of April and the resulting thawing, 

 Summit becomes, next to the high mountain station at Tamarack, the 

 coldest locality. As the spring advances and the accumulated snow 

 becomes less, the mean temperature rises and causes Summit to become 

 relatively warmer than the other stations till by the end of summer 

 it is the warmest of the series, a position of advantage maintained for 

 the rest of the year. 



The highest station whose climate is to be considered is Tamarack. 

 Its altitude prevents Tamarack from ever becoming warm for very 

 long; unlike the other stations, at no time in the year is its climate 

 the warmest of the series. At the beginning of the year, the coldest 

 station except Bridgeport, it becomes the coldest in April as a result 

 of the relative rise of Bridgeport , and remains the station with the 

 lowest mean temperature till August, when it becomes warmer than 

 Fordyce and in late fall and early winter (October-November), 

 warmer than both Fordyce and Bridgeport, but it closes the year the 

 next coldest station. 



