FOREST TREES OF THE PACIFIC SLOPE. 213 



Approximately 75 species occur on this continent, while ahout 20 are trees, 

 13 of which inhabit the Pacific region, into which one extends from the Atlan- 

 tic States. The willows are of very ancient origin. Remains of them exist in 

 the Cretaceous formations of our Middle West, while willows appear to have 

 flourished extensively on this continent and in Europe during the Miocene 

 period. 



With few exceptions the various species of willows, which, as a class, are 

 nearly always distinguished as willows from other trees and shrubs by laymen, 

 are exceedingly difficult to identify, especially before they become trees. When 

 they have attained tree size most of the important ones can be distinguished 

 by a careful study of their mature leaves, bark, twigs, and habit of growth. 

 But individual trees are likely to be found which will baffle attempts at identi- 

 fication without a close examination of the minute characters of the male and 

 female flowers and the tiny seed capsules, all consideration of which is here 

 omitted. Such an examination requires a strong magnifying lens and a good 

 knowledge of plant morphology: 



Black Willow. 



Salii- nigra Marshall. 



DISTINGUISHING CHARACTERISTICS. 



Black willow is the largest and most widely known of our tree willows, but 

 much less abundantly represented in the Pacific country than in its eastern 

 range. It is more distinctly a tree throughout its range than almost any of our 

 other tree willows, and for this reason it is probably the most commonly recog- 

 nized. Several trunks grow close together. Its usual size is from 25 to 50 feet 

 in height and- from 10 to 20 inches in diameter. Trees from 60 to SO feet high 

 and from 2 to 3 feet in diameter are of rather rare occurrence. The trunks 

 (rarely straight) are usually somewhat bowed and leaning, but are clear of 

 branches for a third or a half of their length in the open, and for two-thirds of 

 it in close stands. The branches trend somewhat upward, forming a wide, 

 round-topped, open crown. Rough, furrowed, blackish-brown bark, with wide, 

 thick-scaled ridges and narrower connecting ridges, is a marked character. 

 The slender, drooping branchlets are very easily snapped off at their bases. 

 The leaves — very variable in size and form — from straight to scythe-like (figs. 

 85, S6), are from 1\ to 5 or sometimes 6 inches long, and pale yellow-green. 

 They may be somewhat shiny above and smooth beneath, or minutely hairy on 

 the veins of the under surface. Wood, pale red-brown, light and soft, rather 

 fine-grained, but firm. It has little or no actual or possible economic value, 

 except for fuel and charcoal. 



Longevity. — Not much is known of its age limits, which in trees from 12 to 

 18 inches in diameter are from 35 to 60 years. Occasional large trees are esti- 

 mated to be from 125 tcl50 years old. Further study of its longevity is 

 required. 



RANGE. 



New Brunswick to southern Florida and west to eastern Dakota, Nebraska, Kansas, 

 Indian Territory, southern Arizona, southern and central California, and south into 

 Mexico. 



California. — Western foothills of Sierras, San Joaquin and Sacramento valleys, north 

 to eastern foothills of coast ranges in Colusa County, and south through southern cross 

 ranges. 



