98 HAND-BOOK OF TREE-PLANTING. 



surface with a board or the back of the spade, 

 or with a light roller. 



" Birches and alders have small and winged 

 seeds that are also produced in catkins. They 

 blossom very early and ripen their fruit usually 

 in the autumn, when they should be collected 

 and laid away to ripen and shed out. These 

 may be sowed in beds at once, or they may 

 be kept over winter in a suitable seed-room, 

 where, after sufficient drying, they should be 

 kept covered from the air. 



i( Mulching will be found serviceable with 

 all these small seeds that are sowed in summer. 

 Freshly-mown grass, short broken straw, or 

 autumn leaves, will do if spread so lightly as 

 to let the sunshine through the material. 



" Some other seeds are endowed with great- 

 er vitality, and may be kept for a longer time 

 out of the ground. The different species of the 

 ash have seeds that belong to this class, and 

 some of them, if kept dry during the winter, 

 will not vegetate until the second year. It is 

 better to sow these in drills in the autumn, 

 or to winter the seeds out-of-doors by throw- 

 ing them upon a hard surface, such as a gar- 



