FOREST TREES OF THE PACIFIC SLOPE. 171 



ward to Mount Adams. but not in Columbia River basin : on east side of Cascades, only 

 in northern part <>n Natcb.es, Tieton, Atanum, and Klickitat river watersheds. Locally 

 noted on Mount Rainier, at 3,500 to 6,000 feet — more common on north than on south 

 side; Goal Mountains; Dewey Lake (head of American Elver), at 5,300 feet, Not 

 detected <»n Mount St. Helens. 



Ohegon. — West side of Cascades southward to Deer Creek (tributary McKinzie River, 

 T. 14 S., R. 6 E.), generally at 2,500 to 6,100 feel elevation. Locally noted on Mount 

 Hood at Government Camp, and on north side <T. 1 N., R. 8 and R. !> B.) ; valley 

 of Saniiam River, at 4.oou to 5,000 feel ; between forks of Breitenbusb River, at 4,150 

 feet. Reported extending 150 miles smith of Mount Hood, but definite records of Its 

 occurrence there are lacking, as are also records of its reported existence in northern 

 Idaho. 



OCCURRENCE. 



Common on bottomland, along streams, in basins, valleys, and gulches, and on moun- 

 tain slopes. Where moisture is deficient, confined chiefly to nortb exposures and north 

 sides of mountains, bul where precipitation and humidity are great, exposure is less 

 Important, and the tree is (•(minion on south slopes. Chiefly In moist, rocky or gravelly 

 soils of good quality ; occasionally, of small size, on poor, dryish soils ; very much like 

 western red cedar In soil requirements. Quantity and quality of soil more important 

 where moisture is deficient or where evaporation is rapid. 



Mainly scattered singly or in groups; sometimes In pure stands of limited extent. 

 Generally with Sitka spruce, western red cedar, western hemlock, grand fir, western 

 yew, broadleaf and vine maple-:, and Sitka alder, in Washington. British Columbia, and 

 south Alaskan coast region ; higher up, with black hemlock, lodgepole pine, alpine, ama- 

 hilis, and noble lirs, Douglas fir, western larch, western white pine, and Engelmann 

 spruce. . 



Climatic Conditions. — Climate of range generally favorable for tree growth. Sum 

 mers comparatively cool and humid, and winters not severe. Average annual precipita- 

 tion from 20 to loo inches or more, from Oregon to Alaska. Changes in temperature 

 are usually gradual, but in places mercury drops considerably below zero. In vicinity of 

 ocean, climate is especially mild and uniform, while humidity and precipitation are par- 

 ticularly great. 



TOLERANCE. Not so tolerant as western red cedar and hemlock, but more tolerant 

 than western white pine and nohle fir. Under besl conditions for growth it maintains 

 fairly dense shade. Tolerance varies with soil, moisture, and climatic conditions. Less 

 tolerant with age. Where soil and air are abundantly moist it thrives in the open ; but 

 partial shade and shelter (reducing evaporation and transpiration) are beneficial when 

 soil moisture is deficient. 



Reproduction. Seeding babits not fully known. Produces cones rather sparingly, 

 hut with occasional rather good seed years. Seed lias only moderate rale of germina- 

 tion, with transient vitality. Reproduces itself freely under favorable conditions (moist 

 soil and shade), but poorly in dry situations. Germination and growth of seedlings best 

 on moist moss, muck, and mineral soils. 



Lawson Cypress; Port Orford Cedar. 



Ohamcecyparis lawsoniana (Murr.) I'arlatore. 



DISTINGUISHING CHARACTERISTICS. 



On account of its great beauty as an ornamental evergreen, Lawson cypress, 

 the Port Orford Cedar of lumbermen, is widely known in litis country and abroad. 

 It is little known, however, as a forest tree. It is the largest tree of its genus 

 and also the largest representative of its tribe I ( 'upressinea- ) in North America. 

 Height, from 125 to 180 feet, with a diameter of from :U to 6 feet. Trees 8 or 

 more feet in diameter and nearly 200 feet high sometimes occur, but are now rare. 

 In youth it is readily distinguished by its profusion of short, feathery, weeping 

 branchlets of deep yellow-green, and its dense, sharply defined, pyramidal 

 crown, which extends nearly to the ground and. in the open, is retained for 

 many years. At first the branches all trend upward, but gradually, as the tree 

 grows older, they become horizontal and drooping, especially at the bottom of 

 the crown. The tips of the leading branchlets anil the fringy side sprays 

 hang down conspicuously, on old trees the leaf-covered twigs being shorter 



