Figure 1. --Location of populations (dots). 



Freezing tests were made to determine levels of hardiness of each population for 

 six dates between August and December of the second growing season. These tests 

 generally followed the procedures outlined by Levitt (1972) . For each sampling date, 

 six sets of 10 lignified twigs (5 to 10 cm in length) were cut from the current 

 growth of seedlings representing each population. Twigs in each set were moistened 

 and packaged in a plastic bag. Although each set contained twigs from 10 different 

 seedlings, all sets did not necessarily contain twigs from the same 10 seedlings. 

 About 15 seedlings from each population were needed to supply sufficient twigs for a 

 single sampling date. 



2 



