2331
CHAV. CX11I. CONI'fWUE. Pl'CEA.
5 P. ;i. 4 cinlrea, Finns /Mcea cintrea Baum. Cat. , ed. 1835, is a low plant with greyish hark,not yet introduced.
Description. The silver fir, the noblest tree of its genus, except P. Webb-iana, rises to the height of from 160 ft. to 180 ft., with an erect stem, regularlyfurnished with whorls of candelabrum-like branches. The trunk, in full-growntrees, is from 6 ft. to 8 ft. in diameter, covered, till its fortieth or fiftieth year,with a whitish grey bark, tolerably smooth ;but, as it increases in age, becoming crackedand chapped. At a still greater age, thebark begins to scale off in large pieces,leaving the trunk of a dark brown colourbeneath. The branches stand out horizon-tally, as do the branchlets and spray, withreference to the main stem of the branch.
The leaves, on young trees, are distinctlytwo-rowed, and the general surface of therows is flat; but, as the trees advance inage, and especially on cone-bearing shoots,the disposition of the leaves in rows is lessperfect. The leaves are, in every stage of the tree’s growth, turned upat the points; but more especially so on old trees, and on cone-bearingbranches. The leaves are of a darker green above than those of any otherfir; and underneath the}’ have two white silvery lines running lengthwiseon each side of the midrib. As the leaves are partially turned up,these silvery lines make a conspicuous appearance in the general aspect ofthe tree; whence its name. The cones are large, and have a magnificentappearance, both before and after they are mature. They are cylindrical,erect, and bluntly pointed at both ends. When nearly full grown, the scalesare of a fine red; and the bracteas are long, and of a light green. The seedsare of an irregular form, enveloped and surmounted with a membranaceouswing, somewhat broader above than below. The roots spread horizontally,not so near the surface as in the spruce fir. They extend to a great distance,and are not so abundantly furnished with fibres as in the case of most of thespruces, nor have they a conspicuous taproot, as is the case, more or less, withall the genus Pinus . The rate of growth of the tree is slow when young, butrapid after it has attained the age of 10 or 12 years. The following scale of theprogress of the silver fir in the Jura, in France , is given by Baudrillart; butits growth in England is much more rapid. The first year, it rises in five orsix weeks after it has been sown, with five or six leaves, and is about J in.in height. The second year, it advances 1 in., retaining the leaves of thefirst year. The third year, it advances from 1 in. to 2 in., indicating therudiment of a small lateral branch. The fourth year, it advances about 2 in.,showing a second lateral branch ; and, if taken up at this time, the plant willhe found to have a small taproot. The fifth year, it begins to grow somewhatmore freely, but still so slowly, that, unless under very favourable circum-stances, the plants are seldom found, at that age, above 9 in. or 1 ft. in height.About the eighth year, they begin to increase more rapidly; gradually length-ening the annual growth of the leading shoot, till, at their 20th year, it is from2 ft. to 3 ft. in length. Cones with fertile seeds are seldom produced beforethe tree has attained its 40th year ; though cones without seeds often appearbefore half that period has elapsed. The female catkins are often produced foryears together, without any males appearing on the same tree. In the Jura , asilver fir, at the age of 20 years, is commonly from 9 ft. to 10 ft. in height, with atrunk from 12 in. to 1ft. 4 in. in circumference. After this, it increases inheight at the rate of from 1 ft. 8. in. to 2 ft. 2 in. a year. At 40 years’ growth,™e trunk is from 3 ft. to 3 ft. 6 in. in circumference ; at 50 years, from 4 ft. ton ft.; at 60 years, from 6 ft. to 8 ft.; at 75 years, from 10 ft. to 11 ft. 6 in.;nnd, at 100 years, about 13 ft. From 100 to 120 years’ growth is necessaryt0 produce a tree of from 114 ft. to 130 ft. in height : after which period, it
liggs
mm