2 TRANS. ST. LOUIS ACAD. SCIENCE. [162 
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. — 
Sizz. Almost all the pine species grow up to be trees ; the only 
shrubby one known to me is Pinus montana, heretofore known 
as P. Pumilio; a few make small, insignificant trees, such as 7. 
tuberculata ; the nut-pines, or cembroid pines, never grow large, 
but several others attain the greatest dimensions; P. Laméer- 
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. tuberculata 
and perhaps P. montana), 300 years (P. mitis, P. ponderosa, 
P. Balfouriana), and 500 to 600 years (observed in P. montz- 
cola and P. Lambertiana). 
The Bark in some species is thin, only a few lines thick, flaky 
and detached in scales (P. contorta, P. restnosa) ; in others (e.g. 
P. ponderosa) it is several inches thick, persistent, rough, and 
deeply cracked. It is gray in some species, e.g. in the nut-pines, 
but most commonly of a brown red or cinnamon color, or some- 
times deeper brown; in P. australis and P. Lilliottiz, especially 
in the latter, it is laminated, the external layers peeling off in 
thin plates. 
The woop 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 GO, i 7. 
insignis 5 and in P. rigida var. serotina 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, Lamber- 
téana, and mitis sometimes roo or even 150 years ; in others, e.g. 
P. flexilis 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 
