CONIFERS OF THE ROCKY MOUNTAIN REGION. 39 



the ripe open cones quickly and is easily disseminated by wind, 

 usually germinating the autumn it is shed, and the seedlings estab- 

 lishing themselves before winter. Germination is abundant and best 

 on moist duff, litter, moss, decayed logs, stumps, etc., both in the 

 open and in the densest shade, where seedlings hold their ground with 

 remarkable power. The tree does not reproduce itself readily 

 where frequent fires have destroyed the ground cover or forest 

 cover to such an extent that soil moisture is materially reduced. 

 Considerable quantities of the seed are eaten by squirrels. 



LONGEVITY. 



Western red cedar is a slow-growing tree and the extreme age 

 attained is at present imperfectly known, chiefly because the centers 

 of the largest trees cut are usually decayed, thus preventing an 

 accurate count of the annual rings of growth. It may, however, 

 be regarded as very long-lived. Trees 24 to 40 inches in diameter 

 are from 200 to 510 years old. Some of the largest trees are un- 

 questionably from 800 to 1,000 years old. 52 



FAMILY RELATIONSHIPS OF YEW TREES. 53 



The trees and shrubs which belong to the family Taxacese (yews 

 or yewlike trees) differ fundamentally from the true cone bearers, 

 Coniferse, in producing male flowers on one tree and female flowers 

 on another, flowers of both kinds very rarely occurring on different 

 parts of the same tree. The conifers usually bear male and female 

 flowers on the same tree, each sort being on different branches or 

 parts of them. 54 



The leaves of Taxaceous plants are evergreen, flat, narrowly 

 lance-shaped, and appear to grow (in our native species) in spreading 

 lines on two opposite sides of the branches (PI. XIII). The fruits 

 differ from those of conifers in being almost or entirely enveloped 

 in a pulpy covering. In the case of the yews of this group it is a 

 small, berrylike, bright-colored cup (PL XIII, a), the hard seed 

 being embedded in a juicy, sticky outer pulp. 



In the case of other members of the family the covering of the fruit 

 is firm, practically complete, and similar in appearance to an olive. 55 



62 See footnote No. 51, p. 36. 



53 The class relationship of the yew trees is briefly discussed in Forest Service Bulletin No. 207, The 

 Cypress and Juniper Trees of the Rocky Mountain Region, p. 3, 1915. 



& 4 There are, therefore, fewer seed-bearing individuals among the yews and their allies than among 

 cone-bearers, since only trees bearing female flowers produce seed. Hence, in thinning a stand of Taxa- 

 ceous timber both male and female trees should be preserved as near to each other as possible if reseeding 

 is expected to take place, for pollen of the male flowers is carried to the female flowers only by the wind. 

 If male trees are distant more than 25 or 30 yards from the female tree, only the strongest wind, blowing 

 at the right time, will effect fertilization. 



" See fig. 75, Forest Trees of the Pacific Slope, p. 192, 1908. 



