CHAPTER I.
ON THE GROWTH AND STRUCTURE OF TREES.
The stems of Exogenous[1] trees may be described as of one uniform structure and mode of increase, and are usually very firm, yielding the most solid and best description of timber, their solidity and strength fitting them admirably for use in carpentry, and for many domestic purposes.
The most common form of stem is the cylindrical, but it is occasionally found grooved or fluted, and not unfrequently flattened, approximating to an oval; the cylindrical form being, for most purposes, the best for conversion into beams, joists, boards, &c.
Botanists speak of the stem as the "ascending axis" of a tree, from its taking an upward direction and giving off branches. In the Elm, these branches take an oblique upward direction; in the Birch, they are also oblique, slightly pendulous, and flexible; those of the Willow are somewhat oblique, with the lateral branchlets pendulous and drooping in graceful curves; in the
- ↑ Exogens are a vegetable class, which augment their woody matter by additions to the outside of that which is first formed; as long, therefore, as they grow a new layer of wood is added to the outside of the previous growth. The Endogen class—i.e., Palms, &c. &c.—differ from the above, in having their substance formed by successive additions from the inside.
