1914] 
GROOM—TRACHEID-CALIBER 
289 
Considering section I of Pinus, it is evident that the first six 
species, characterized by the narrowest spring tracheids, all occupy 
sites that are both edaphically dry and climatically dry for long 
TABLE I 
Pinus, section I 
P. cembroides. . . 
P. Parryana..... 
P. Balfouriana, . 
P. monticola. . 
P. Lambertiana.. 
MEAN DIAMETER OF 
SPRING TRACHEIDS IN # 
HaBirat* 
Pacific or 
Atlantic North 
Mest 
oe eae 24.0 | Dry pee dry gravel, Arizona, Mexico, at 
tees 24.5 Diy mesas, slopes, dry gravel, Colorado, 
xas, New Mexico, up 
7 RRS eas 22-6 And yee and desert oy ast subtropical in 
California and Lower 
Bakes csi avy 33.0 ey gravelly slopes, Utah a California, Ari- 
a, at 3000— 
Saas Gees 32.0 Often alpine, 5000-11,000 ft.; 7 or rocky 
ridges and ee in Californ 
ae See 33-5 | Often alpine 0 12,000 ft * ae gravelly 
ridges in California, Nevada, Arizona, and 
Colorado. 
5 ae res 35.0 | Alpine; 53° N. to British Columbia to south 
rn California, uae it reaches 10,000 ft. 
thee eee 39.0 | Sandy-gravelly, sunny places, from British 
Columbia down to Texas, Arizona, S.E. 
California, attaining an altitude ot 12 000 
ft. in Montana; po sents also in Color. ado. 
a ae 39-5 weet _ ravi — at 8000 ft. in New 
and A 
rb ed Ope ee wideaienel | in Cabada and particularly the 
northeast of the United States; in the 
north on moist sandy or even swampy rites 
but i . hee southern part of its area also o 
dry 
ae 43.0 British "Columbia, southward to California, 
etc., ooo ft.; in cultivation pre- 
fers ary, @ fhe : miter asian situations 
eos cok 45.0 Cascade and Coast Ranges in Oregon, so 
*F, : 
or particulars as to the habitats of the A 
Cited works of H. Mayr and C. S. SARGENT. 
pe ie . Dy ees ees 
paper, I rely mainly 
Pai two of them are also alpine species. The seventh species, 
aulis, also is alpine, but at least in the north is in a moister 
te 
are the preceding six, and there is no record that it is 
on a very pervious soil. The eighth, P. flexilis, is i alpine than 
