294 A HANDBOOK OF CONIFERiE 



L. occidentalis is found in the Columbian Basin between the 

 Rocky Mountains on the east and the Cascade Range on the 

 west ; also north of the Blue Mountains of Oregon, at altitudes 

 ranging from 2,500-6,000 ft. It is said to attain its greatest 

 dimensions in Montana, where it is common. David Douglas 

 discovered this species in April, 1826, at the Battle Falls on the 

 Columbia River. Seedlings were raised in the Arnold Arboretum 

 in 1880, and young plants were received at Kew in 1881, which 

 mark the introduction of this tree to Europe. 



Wood very similar in appearance to European larch, of 

 excellent quality, hard, strong, and durable in contact with the 

 ground, and credited with being harder and stronger than either 

 the E. American or European species. A report on the results 

 of tests on green material shows :^ 



Weight, green (moisture 25 per cent., wood 75 percent.), 40 lb. 

 per cu. ft. 



Tension, strength across the grain, 230 lb. per sq. in. 



Compression, strength across grain at elastic limit, 560 lb. 

 per sq. in. 



Compression, crushing strength with the grain, 3,800 lb. per 

 sq. in. 



Shearing, strength with the grain, 920 lb. per sq. in. 



Bending, modulus of rupture (breaking strength), 7,500 lb. 

 per sq. in. 



Bending, modulus of elasticity (stiffness), 1,350,000 lb. per sq. in. 



Hardness, weight required to imbed a 444 in. steel ball, 

 460 lb. per sq. in. 



The timber of the western larch is used for telegraph and 

 telephone poles, railway sleepers, building material, flooring, 

 ships and barges, posts and rails, and for firewood. As fuel it 

 is reputed to be superior to all other American coniferous woods. 

 The total stand of western larch timber in British Columbia is 

 computed to be 3,152,000,000 board ft.^ The annual cut is 

 between 38,000 and 39,000 board ft. 



In America a sweet manna-like substance exudes from the 

 tree and is sometimes eaten by the Indians. A specimen of this 

 substance, reddish brown in colour, is preserved at Kew. A 

 whitish resinous exudation is found upon trunks and branches 

 of young trees of L. occidentalis at Kew, but has not been 

 noticed on other larches. 



The original trees received at Kew in 1881 were planted in 

 well-drained, poor, sandy soil and have grown at a similar rate 

 to trees of European larch with which they were mixed. It is 

 a remarkable fact, however, that whilst the European larch is 

 often very badly attacked by Chermes the Western larch remains 



1 Tests by U.S. Dept. Agric— Timber Exhib. Cat., London, 1920. 

 ^Whitford and Craig, Forest Res. British. GoJ. 241 (1918). 



