30 BULLETIN 460, u. s. department of agriculttjbe. 



description of the tree's characteristics) in his account of the dis- 

 covery of the species published in 1836. 1 



The botanical history of western yellow pine is full of perplexities. 

 During the three-quarters of a century the tree has been known, no 

 less than 15 different technical names have been applied to different 

 or the same forms of the tree, some of which were described as distinct 

 species and others as varieties. Much, if not all, of this confusion 

 is probably the result of a study of herbarium specimens only, rather 

 than of the tree as it grows under the different soil and climatic con- 

 ditions within its extensive range (Map No. 10). 



DISTINGUISHING CHARACTERISTICS. 



Pinus ponderosa is a massive, straight-trunked tree with a long, 

 narrow, open crown of hugely developed, bent branches. The nar- 

 row columnar form of the crown, with its scattered branches, up- 

 turned at their ends, is very characteristic. Often one or two large 

 lower branches are separated from the crown by 20 or more feet of 

 clear trunk. Trees grown from the first in an open stand usually 

 bear branches close to the ground, retaining this long, low crown 

 throughout life (PL XX) . The trunk is cylindrical, with little taper 

 until the large crown branches are reached. Its majestic size is sur- 

 passed by no other native pine except the sugar pine of California. 

 In general the height is from 125 to 140 feet, with a practically clear 

 trunk of from 40 to 60 feet, and a diameter of from 3 to 5 feet. 

 Unusually large trees are from 150 to 180 feet high, while trees are 

 said to have been found over 200 feet high. The largest diameter 

 recorded is about 8 feet. The form of western yellow pine found in 

 the central and southern Rockies ranges from 60 to 125 feet in height 

 and from 20 to 30 inches in diameter, or occasionally somewhat 

 larger. The bark of old trunks is marked by very broad, shield- 

 like, russet-red plates, which may be from 3 to 4 inches thick, espe- 

 cially near the base of the tree. The bark is peculiarly made up of 

 small, concave scales. Younger trees, up to 2 feet in diameter, are 

 quite unlike older ones in having dark red-brown or blackish, nar- 

 rowly furrowed bark. 2 Young shoots, which have a strong odor of 

 orange when broken, are yellowish green and later brownish. 



1 Companion to the Botanical Magazine, ii. 111. 1836. 



2 Lumbermen in the range of western yellow pine distinguish two forms of the species, 

 one of which they call " black jack " and the other " yellow pine." The two forms are 

 botanically alike, but distinguished by striking differences in the color and markings of 

 the bark, which appear to be due entirely to age. Trees up to about 150 years of age 

 commonly have blackish, narrowly ridged hark and are, therefore, known as " black 

 jack," while trees older than these usually bave light reddish-brown bark broken into 

 broad, flat ridges, such trees being called " yellow pine." The young growths of several 

 eastern pines are also distinguished as " black jack," most lumbermen who apply the name 

 knowing, however, that it is an age designation rather than one of species. 



