Trees of the Northern United States: Their Study, Description and DeterminationApgar, A. C. (Austin Craig)
Science
Trees of the Northern United States: Their Study, Description and Determination
Apgar, A. C. (Austin Craig)
Trees -- North America
All the dry, scaly fruits, usually formed by the ripening of some sort
of catkin of flowers, will be included under the term _cone_. Pine,
Alder, [Illustration] Magnolia. If the appearance of the fruit is not
much different from that of the cluster of flowers, as in the Hornbeams,
Willows, and Birches, the term _catkin_ will be retained for the fruit
also. The scales of a cone may lap over each other; they are then said
to be _imbricated_ or _overlapping_, [Illustration] (Pine); or they may
merely touch at their edges, when they are _valvate_ [Illustration]
(Cypress). When cones or catkins hang downward, they are _pendent_. If
the scales have projecting points, these points are _spines_ if strong,
and _prickles_ if weak. The parts back of the scales are _bracts_; these
often project beyond the scales, when they are said to be _exserted_.
[Illustration] Sometimes the exserted bracts are bent backward; they are
then said to be _recurved_ or _reflexed_.
CHAPTER V.
_Winter Study of Trees._
Many of the peculiarities of trees can be studied much better during the
winter and early spring than at any other time of the year. The plan of
branching, the position, number, size, form, color, and surface of buds,
as well as the arrangement of the leaves within the bud and the
peculiarities of the scales that cover them, are points for winter
investigation.
GENERAL PLAN OF BRANCHING.--There are two distinct and readily
recognized systems of branching. 1. The main stem is _excurrent_ (Fig.
3) when the trunk extends as an undivided stem throughout the tree to
the tip; this causes the spire-like or conical trees so common among
narrow-leaved evergreens. 2. The main stem is _deliquescent_ (Fig. 4)
when the trunk divides into many, more or less equal divisions, forming
the broad-topped, spreading trees. This plan is the usual one among
deciduous trees. A few species, however, such as the Sweet Gum and the
Sugar-maple, show the excurrent stem while young, yet even these have a
deliquescent stem later in life. The English Maple and the Apple both
have a deliquescent stem very early.
All the narrow-leaved evergreens, and many of the broad-leaved trees as
well, show what is called _definite_ annual growths; that is, a certain
amount of leaf and stem, packed up in the winter bud, spreads out and
hardens with woody tissue early in the year, and then, no matter how
long the season remains warm, no additional leaves or stem will grow.
The buds for the next year's growth then form and often become quite
large before autumn.
There are many examples among the smaller plants, but rarely one among
the trees, of _indefinite_ annual growth; that is, the plant puts forth
leaves and forms stems throughout the whole growing-season. The common
Locust, the Honey-locust, and the Sumacs are illustrations.
Public-domain text, read in full here on John Shaqi.
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