DURATION OF LEAVES IN EVERGREENS 
These branches attain a growth usually of less than 5 centimeters in a 
season, and may bear no more than 3 leaves on a season's growth. 
However, leaves of '3 or 4 years' growth have been found which were 
from 20 to 30 mm. in length, while the species description, Frye and 
Rigg (2), gives leaves 6 to 17 mm. long. 
(b) While evergreen leaves are quite common, they are not usual 
on mature shrubs, and there seem to be no definite external factors 
which will explain their appearance or non-appearance. At best, 
only a few branches bear evergreen leaves. Also, of two shrubs of 
approximately the same age, growing under apparently the same con- 
ditions, and standing only 3 or 4 meters apart, one may be entirely 
devoid of leaves and the other have several branches bearing leaves of 
3, 4, 5 or even 6 years' duration. The extreme duration observed was 
6 years. 
12. Arbutus menziesii Pursh. Observations were made on the 
campus of the University of Washington. The leaves begin to fall 
early in June of their second year. Many of the trees put on a second 
growth late in the summer, whose leaves are somewhat smaller and 
lighter in color than the normal spring leaves, and this gives the 
appearance of two seasons' growth. During the extreme and unusual 
cold weather of the past winter, many of the spring leaves were killed 
by frost while the late summer leaves seemed to be scarcely affected. 
This enhances still more the appearance of two seasons' growth. 
13. Ceanothus velutinus Dougl. Like Arbutus menziesii, this nor- 
mally holds the leaves of one season only until those of the succeeding 
season are fairly matured; that is, for a period of about 15 months. 
14. Linnaea americana, Forbes. This trailing vine, as a rule, does 
not drop its leaves, but the leaves simply decay while attached, as 
they lie against the damp moss or already decaying leaves of the sub- 
stratum. They persist throughout the winter, and in many cases 
until after the flowering season in the spring. 
15. Micromcria douglasii, Benth. The same condition is found in 
this as in Linnaea americana. 
16. Rubus laciniatus Willd. This plant has escaped from cultiva- 
tion, and is commonly known as the "evergreen blackberry." Some 
leaves persist at least until after the flowering season. 
17. Rubus ursinus Schlecht. & Cham. This is common on logged- 
off lands; according to Frye and Rigg (2) it is evergreen only in western 
Washington. 
