DIRECT SOWING. 147 



b. Age. 



The germinating power of seed is greatest immediately 

 after ripening ; it can be maintained for a shorter or longer 

 period according to species and treatment. It follows that, the 

 sooner seed is sown after ripening the better. This becomes 

 absolutely necessary in the case of elm seed, as it only keeps 

 for a very short time. The seeds of birch, alder, silver fir, 

 sweet chestnut, beech and oak may be kept until the following 

 spring, but on no account should seeds of these species be 

 used more than six months old. In the case of lime, horn- 

 beam, maples, ash, larch, spruce and Scotch pine seed up to 

 two years old may be used ; if older it should be rejected. 



When seed is stored it must be kept free from moisture, 

 and protected against heating by keeping it in an airy locality 

 and turning it over from time to time. 



c. Source. 



The source whence seed has been obtained is of importance. 

 Although trees of all ages can yield excellent seed, as a general 

 rule it may be said that, the best seed is derived from trees 

 which are in the prime of life, namely, healthy trees with a 

 full crown, which have just completed their principal height 

 growth. At the same time, soil and climate, and especially the 

 latter, are of greater importance than the age of the trees. 



The question has been raised, whether it may be advan- 

 tageous to obtain from time to time seed from another locality, 

 as is done in agriculture. This may become desirable when 

 the trees are affected by disease or by peculiarities which are 

 transmitted through seed, as for instance twisted fibre ; apart 

 from such cases, it is probably better not to change the seed. 

 Trees live for a long space of time, and they accommodate 

 themselves to a locality, so that home seed is likely to do best. 



d. Testing Seeds. 

 The quality of seeds can be judged by their external and 

 internal appearance. Good seeds fill up the outer coat, are 



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