28 THE ESSEX NATURALIST
deal or Baltic whitewood of commerce—and it is largely used
for constructional woodwork in houses, especially in Northern
England and Scotland. Because it does not contaminate food-
stuffs, it is in demand for boxes used for food containers, while
it is also used for wood wool and paper pulp, its long tracheids
rendering it valuable for paper-making. Spruce is also used for
scaffold poles and the sides of ladders and, because of its excellent
resonating properties, in the manufacture of musical instruments.
Of recent years much Sitka Spruce (P. sitchensis (Bong.)
Carr.) has been planted in Britain. The timber resembles that
of European spruce, but tends to have a somewhat greyish
(silvery) sheen. It can be put to similar uses, but it is a more
valuable wood and better grades are used in aeroplane con-
struction and for hollow masts and spars of racing yachts.
Similar to the woods of the spruces are those of the Silver
Firs; in fact, that of the Common Silver Fir (Abies alba Mill.)
is sometimes mixed with spruce and sold under that name.
Used, like white deal, for constructional work, the timber of
silver fir is not durable, and must be preserved if used in the
open. Since the wood is practically free from resin it is specially
valuable for food containers and, incidentally, for kindling wood,
since it does not throw out sparks. The European silver fir is
little planted now, for it is prone to a number of diseases, but
two western North American species, the Giant Fir (A. grandis
Lindl.) and the Noble Fir (A. nobilis Lindl.) have been planted
experimentally, with promising results so far. The latter species
produces a wood of rather better quality than A. alba.
The Common Larch (Larix decidua Mill.) although extensively
planted in Britain, is a native of the mountainous regions of
central and southern Europe. Its wood is hard and fairly heavy,
with a pale brown to reddish brown heartwood and a narrow,
yellowish sapwood; there is a marked difference between spring
wood and summer wood. The heartwood is very durable, and
is valuable for fence posts, gates and similar outdoor work,
but the sapwood requires preservative treatment before it is
used in the open. It is a valuable timber for pit props and
is also useful for boatbuilding, piling, breakwaters and flooring.
Larch Canker (Dasyscypha calycina (Schum.) Fuckel), a fungus
which damages the stem, is a great menace to European larch,
although the Japanese Larch (L. leptolepis (Sieb. and Zucc.)
Murr.), which produces a somewhat similar timber, seems less
liable to its depredations. The Dunkeld Larch (L. eurolepis
Henry), which is apparently a hybrid between the two former
species, has not been cultivated long in Britain, although so far
it appears to be more vigorous than either European or Japanese
larch, and to remain free from canker.