42 BULLETIN 460, U. S. DEPARTMENT OF AGRICULTURE. 



scant, and uneven; but reproduction on burned-over lands is, with 

 aid of fire (which opens the cones) , exceedingly thick and even. Full 

 light and exposed mineral soil are requisites of good reproduction. 

 This favorable condition of the soil is produced by fire, which, 

 when it does not consume the cones, leaves them open or in condition 

 to open and release their seeds. 



LONGEVITY. 



Lodgepole pine attains an age of from 100 to 175 years, but doubt- 

 less it is capable of reaching from 200 to possibly 300 years, if pro- 

 tected from fire, to which it quickly succumbs on account of its thin 

 bark. Few stands have in the past attained an age of over 60 years 

 before being killed by forest fires. 



JACK PINE. 



Pinus bariksiana Lambert. 



COMMON NAME AND EARLY HISTOBY. 



Pinus hanksiana does not occur within our Rocky Mountain region, 

 but it enters the Canadian territory immediately north of this region 

 (map Xo. 14) and it is included here in order to present an account 

 of all the pines in the Rocky Mountain region irrespective of national 

 boundaries. 



Jack pine is best known to the public as a tree of southeastern 

 Canadian provinces and of our Great Lakes country, where it is 

 variously called jack pine, scrub pine, black jack pine, gray pine, 

 black pine, Banksian pine, and Hudson Bay pine. The name jack 

 pine is, however, widely used and perhaps the most appropriate. 



There appears to be no authentic record of when jack pine was 

 first discovered. It must have been well known to the French ex- 

 plorers and settlers of eastern Canada at least as early as the sixteenth 

 century. Strangely enough the first record of its existence is based 

 on trees cultivated in England, 1 where the species is believed to have 

 been planted prior to 1735. By whom and from what part of its 

 range in this country the seeds or plants were sent to England is 

 unknown. It seems likely, however, that seeds were sent from east- 

 ern Canada. The first technical name, Pinus sylvestris, 8 divaricata 

 Aiton, given to this tree was published in 1789 by William Aiton, 

 a Scottish botanist and gardener, who based his brief descrip- 

 tion of it on trees growing in the Royal Botanical Garden at Kew, 

 England, of which he was then director. Correctly speaking, the 

 logical name for this pine should be Pinus divaricata (Ait.) Du 

 Mont de Courset, which is based on this early one of Aiton. But 



1 Loudon, Arb. et Frut. Brit., iv, 2192. 1838. 



