REST PERIOD STUDIES WITH SEEDS 



29 



Results of Forcing Seeds of Woody Plants. Seeds of woody plants 

 were treated in various ways for three general purposes : first, to find 

 what species seem to have a rest period; second, to test the various 

 treatments used for breaking the rest (Table 11) ; and, third, for 

 testing effects of treatments on total percentage of germination (Table 

 12). The results shown in the two tables were then summarized in 

 Table 13. A review of the experiments and summary will be of in- 

 terest. 



TABLE 13. SUMMARY OF TABLE 11, EFFECTS OF TREATMENTS ON THE REST 

 PERIOD, AND TABLE 12, EFFECTS OF TREATMENTS ON TOTAL GERMINATION 



Of the 31 species tested (Tables 11 and 12), the following 11 

 failed to make any germination whatever: 



Betulaceae 

 Ostrya virginiana, L. 

 Carpinus caroliniana, L. 



Rosaceae 



Prunus Persica, (L.) Stokes. 

 Crataegus coccinea, L. 

 Pyrus Scheideckeri, Hort. 

 Pyrus fastigiata bifers, Hort. 



Leguminosae 

 Robinia Pseudo-acacia, L. 



Rutaceae 



Ptelea trifoliata, L. 



Celastraceae 

 Euonymus atropurpureus, Jacq. 



Cornaceae 



Cornus asperifolia, Michx. 



Caprifoliaceae 



Symphoricarpos vulgaris, Michx. 



Those species requiring more than two weeks for germination, 

 or which made no growth, where planted at maturity (Table 11, col- 

 umn 1), evidently have a rest period. Also those that showed no 

 growth at all (see list following Table 12) may be counted as having 

 a period of rest. Apparently, then, 93.5 per cent of the list of species 

 tested have a rest period. 



The treatment that produced the earliest growth in seeds was the 

 freezing in stratification followed by etherizing twenty-four hours. 



