xed_: blade folded crosswise, thus bringing it
upon the footstalk. Tulip-tree. _Conduplicate_: blade folded along the
midrib, bringing the two halves together. Peach. _Plicate_: folded
several times lengthwise, like a fan. Birch. _Convolute_: rolled
edgewise from one edge to the other. Plum. _Involute_: both edges rolled
in toward the midrib on the upper side. Apple. _Revolute_: both edges
rolled backward. Willow. _Obvolute_: folded together, but the opposite
leaves half inclosing each other. Dogwood.

CHAPTER VI.

_The Preparation of a Collection._

[Illustration: Fig. 16.]

Three specimens are needed of each kind of tree: one, a branch showing
the flowers; another, showing the fruit--one of these, and in many cases
both, will show the leaves. The third specimen, cut from a large limb or
trunk, shows the bark and the wood. This should be a specimen with a
surface so cut as to show the wood in the direction of the silver grain,
_radial section_; with another surface cut in the direction of the
annual layers, _tangential section_; and with a third cut across the
grain, _cross-section_. It should be a specimen old enough to show the
change of color in the heart-wood. By taking a limb or trunk 8 inches in
diameter, all these points can be secured. A specimen cut as shown in
the figure will illustrate all the desired points. Side E F G shows
sap-and heart-wood in tangential section; side A B D C shows the same in
radial section; end A B F E, in cross-section; and B F G D shows the
bark. The central pith is at I; the heart-wood extends from C to J; the
sap-wood from J to D. The silver grain is well shown at the end, and the
blotches formed by it on the radial section.

By having the piece made smooth, and the upper part down to the center
(H) varnished, the appearance of the wood in furniture or inside finish
will be illustrated.

The specimens should be as nearly uniform in size as possible. If a limb
8 inches in diameter be taken and a length of 6 inches be cut off, the
section A B D C should pass through the line of pith; the section E F G
should be parallel with this at a distance from it of two inches; and
two inches from the line of pith, the section A E C should be made. The
whole specimen will then be 6 inches wide and long, and 2 inches thick.

The twigs containing leaves, flowers and fruit need to be pressed while
drying in order that they may be kept in good form and made tough enough
to be retaine