SEED-PRODUCTION. 37 



growth, and falls off when the seed-producing stage is entered. 

 Oak, Beech, Elm, Ash, Maple, Sycamore, Chestnut, Hornbeam, 

 Lime, Alder, and Birch mainly produce stool-shoots ; while 

 Aspen, Robinia, Rowan, non- indigenous Willows and Poplars, 

 and White Alder mainly produce root-suckers. But Chestnut, 

 English Elm, and Lime also throw up a good many suckers, 

 which can be severed and transplanted like seedlings ; and they 

 can easily be propagated by layering, while Willows and Poplars 

 can easily be raised from slips or cuttings. 



In seed-production, trees bearing small fruits with small seeds 

 are much more prolific than those bearing large fruits with 

 heavy seeds. They seed more frequently, and the seeds are 

 carried farther by wind ; hence, even though the germinative 

 power of their seed be less, the average regenerative power of 

 Willows, Poplars, Alder, Birch, Scots Elm, Maple, Sycamore, 

 Pines, Spruces, Douglas Fir, and Cypresses is greater than in 

 Silver Fir, Beech, Oak, and Chestnut. Seed-production is most 

 prolific when trees have completed their main growth in height 

 and begun to expand their crown, as their vital energy is then 

 greatest. Good soil, warm situation, and a free growing-space 

 favour seed-production. Birch, Alder, Larch, and Scots Pine 

 begin to bear seed at about twenty years of age, but Oak and 

 Beech not until about the sixtieth year. The best quality of 

 seed is produced by middle-aged trees, which is preferable to 

 that gathered from trees just beginning to bear or from very old 

 trees. The seed of most trees germinates in the spring after 

 it has been shed ; but Birch, Elm, Aspen, and Willow seeds 

 sprout soon after they fall, while Ash, Hornbeam, Maple, and 

 Sycamore seeds may germinate freely only in the second spring. 



Some idea of average regenerative power may be formed from the 

 following table, but both the size and the weight of the seed, and also its 

 germinative capacity, depend greatly upon the quality of the soil and 

 situation, and upon favourable climatic conditions : 



