8 BULLETIN 680, U. S. DEPARTMENT OP AGRICULTURE. 



advantage of this intolerance is partly overcome by early rapid 

 height growth, which carries the tree above its suppressing heavier- 

 foliaged associates. It appears to be more tolerant on moist soils 

 than on dry ones. In moist sites it occurs in fairly dense stands, 

 and the trees are tall and with clear boles, but the lower branches 

 are early killed and dropped; on drier soils, where open stands or 

 isolated trees are more common, the branches are often retained for 

 many years down to the ground. 



Western larch is a prolific seeder, but it is locally variable in seed 

 production, sterile periods of one or more seasons being common. 

 It rarely bears seed as early as the twenty-fifth year, but begins to 

 produce it abundantly when 40 or 50 years of age. The seed has a 

 fairly high rate of germination and moderately persistent vitality. 

 The thin scales of ripe cones open and close readily with alternate dry 

 and wet weather, so that the period and the rapidity of seed dis- 

 persion vary somewhat with local climatic conditions. Usually, 

 much seed is shed on the snow. Abundant moisture in the soil is 

 required for germination of the seed and growth of the seedlings. 

 The chief competitor of larch is lodgepole pine, the soil conditions 

 for the reproduction of these trees being very similar, as is shown by 

 their frequent association. Both find suitable seed beds in burned- 

 over areas with exposed mineral soil, where the order of reproduction 

 frequently depends upon whether the larch or pine has seeded the 

 ground first. If lodgepole pine has the start, it shades out the much 

 more intolerant larch. If both species start together, larch may 

 preserve its numerical importance in the stand by more rapid height 

 growth. Its light foliage can not prevent the growth of the pines, 

 nor of spruce and firs, the typical occurrence of larch under these 

 circumstances being in mixed stands. Favorite areas for pure larch 

 reproduction are those so thoroughly burned over as to preclude the 

 immediate heavy reproduction of lodgepole pine. 



LONGEVITY. 



Western larch is a long-lived tree,- attaining an age ordinarily of 

 from 300 to 500 years, while the largest trees are from 600 to 700 

 years old. Trees from 16 to 25 inches in diameter are from 225 to 

 300 years old. 



ALPINE LARCH. 



Larix lyallii Parlatore. 



COMMON NAME AND EARLY HISTORY. 



Larix lyallii is a little-known species, which is usually not distin- 

 guished by the ordinary observer from Larix occidentalis, most 

 travelers in its high mountain habitat recognizing it only as a "tam- 

 arack" or " larch," while some have supposed it to be only a high 



