l63 TRANS. ST. LOUIS ACAD. SCIENCE. 



Not satisfied with such superficial knowledge of this interest- 

 ing and important genus of trees, I have for a number of years 

 devoted my leisure hours to the careful study of the different spe- 

 cies accessible to me. In the following pages I give the principal 

 results of my investigations. 



Size. Almost all the pine species grow up to be trees ; the only 

 shrubby one known to me is Phzus niontana^ heretofore known 

 as P. Pumilio ; a few make small, insignificant trees, such as P. 

 tuberculata ; the nut-pines, or cembroid pines, never grow large, 

 but several others attain the greatest dimensions ; P. Lamber- 

 tiana grows to the height of 300 feet, with 20 feet in diameter, 

 and P. ponderosa (at least in California) comes very near it ; 

 these two are probably the largest pines known. 



The AGE of pines varies between 15 to 25 years {P. iiibej-ctdata 

 and perhaps P. juontana)^ 300 years (^P. mitis^ P. ponderosa^ 

 P. Balfouriana)^ and 500 to 600 years (observed in P. monti- 

 cola and P. Lainbertiana. 



The BARK in some species is thin, only a few lines thick, flaky 

 and detached in scales {^P. contorta^ P.resinosa) ; in others (e.g. 

 P. ponderosa) it is several inches thick, persistent, rough, and 

 deeply cracked. It is gray in som.e species, e.g. in the nut-pines, 

 but most commonly of a brown red or cinnamon color, or some- 

 times deeper brown ; in P. austral is and P. Elliott it, especially 

 in the latter, it is laminated, the external layers peeling off in 

 thin plates. 



The WOOD grows rapidly, especially during the first (often the 

 first 50) years of their age, so that annual rings are sometimes 2 

 or 3 lines thick ; in P. glabra I have seen them even 6, in P. 

 insignis 5 and in P. rigida var. serotiiia 4 lines thick ; in old 

 age or in the short seasons of high altitudes the wood grows so 

 slow that sometimes ten annual rings make not more than the 

 thickness of one line. 



The sapwood is always white, and it takes many years before 

 it turns into perfect or heartwood : in P. ponderosa^ Lainber- 

 tiana, and mitis sometimes ico or even 150 years ; in others, e.g. 

 P.Jiexilis and Sabiana not more than 20 or 30 years ; but the 

 majority of pines which I have examined may require 50 or 60 

 years to mature their heartwood. In many other trees this pro- 

 cess takes about 20 or 30 years, in most oaks on an average 



