160 SEEDING AND PLANTING 



26. CLEANING THE SEED 



Seed can be separated from the detached wings and other refuse 

 matter by turning it on a canvas in the open with a winnowing 

 shovel or by slowly pouring it from one basket to another through 

 a current of air. By the exercise of due care the wings and light, 

 worthless seed, as well as broken fragments of cone scales and other 

 foreign matter, can be removed. This method is usually practiced 

 when only a small amount of seed is handled. When large quan- 

 tities are cleaned ordinary grain-fanning mills or specially con- 

 structed cleaning mills are more economical and more effective. 

 Forced draft and properly arranged screens not only remove 

 the dust, dirt, broken cone scales, and leaves but also most of 

 the blind and otherwise overlight seed. After the seed is cleaned 

 it is sacked or placed in carboys or boxes and is ready for storage 

 or shipment. 



27. Species that Require Special Treatment 



The cones of red pine, Monterey pine, knobcone pine, and several 

 other coniferous species cannot be satisfactorily opened by expos- 

 ing them to solar or artificial heat without preliminary treatment. 

 Before drying, they should be submerged from 5 to 20 minutes 

 in water heated to a temperature of 130 F. On their removal 

 from the water they should be spread out in the open air. After 

 this preliminary treatment they open much more readily by either 

 solar or artificial heat. 



In particularly resistant species as in the European larch the 

 cones after drying are shredded or torn in pieces in specially con- 

 structed machines. 1 Somers has recently used a machine quite 

 similar to the ordinary grain threshing machine for extracting 

 the seed of the western yellow pine. The cone scales are loosened 

 or torn off in the machine and the seed liberated. 



28. Seed-extracting Plants 



A seed-extracting plant should be located at the point of great- 

 est accessibility to the entire region from which the seed is drawn 

 and from where the cleaned seed can be distributed at the least 

 cost. Cones are usually bulky, and the directness and shortness 

 of the haul by wagon and rail transportation are important 

 1 Schlich, Wm.: Manual of forestry, vol. V, p. 765. London, 1908. 



