EXERCISE XIII.

Petioles, Surfaces, and Colors.

THE following schedule has three new questions added to it. The first is Petiole? The shape of the petiole, whether round, roundish, or half-round, should be observed, and written down. And if it be remarkable for its length or shortness, if it be unusually limber, or unusually stiff, you must mention these peculiarities about it.

COLOR? To this question the answer is easy. Leaves are sometimes light green, sometimes dark green; and sometimes the upper surface is one color, and the lower another. There are spotted and striped leaves, and some leaves have a brownish or reddish tinge. All these things are to be noted when you see them.

SURFACE? Observe whether the surface of a leaf has hairs or not. If it has hairs, write hairy after this question; but, if it has no hairs, write glabrous, which means free from hairs.

Again, surfaces are either smooth or rough, observe which, and write the result in the schedule.

Some leaves have a very shiny surface, and some are very dull, and these differences should be ob served, and written down; but these qualities need not be noted unless they are strongly marked.

These characters cannot be conveniently represented by pictures, but they are readily seen in actual leaves. Feeling sure that you can easily make them out, we have not attempted to describe a leaf in schedule eight.

The schedule is now made up of the following questions:

NOTE.-While in a book we must present one definite order of exercises, it is well if teachers use their own judgment in adhering to this order. Often, doubtless, much will be gained by judicious deviation. There are minds that demand variety, or their interest flags; and the minds of children, especially, are liable to grow weary of continued attention to one class of objects. Before proceeding with the exercises upon compound leaves, it may, therefore, be advisable to turn to the chapter upon the Inflorescence, or that upon the Flower, and occupy a little time with the opening exercise in which the names of parts are brought before the mind. The identification and naming of the parts of the flower will be easier to most children than the discrimination of simple and compound leaves; while dealing with another and more showy portion of the plant will stimulate the attention.

The use of schedule eight

SCHEDULE EIGHT.

Kind?

Venation?

Margin?

Base?

Apex?

Lobes?

Sinuses?

Shape?

Petiole ?

Color?

Surface?

should, however, still be kept up, and, after a little while, the pupil will come back to the study of compound leaves with a fresh relish for the subject.

SIMPLE LEAVES have only one blade.

COMPOUND LEAVES Consist of several distinct blades, called leaflets. You may know leaflets from lobes by their being entirely separate from each other.

Up to this time I suppose that pupils have described leaflets as leaves; but they must now be careful not to make this mistake. Let them confine themselves to simple leaves in using schedule eight, and write simple leaf upon it, to show that they have considered the matter.

It is sometimes a very nice point to decide between a deeply-lobed leaf and a compound leaf. If

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confusion at first arises, it must be patiently borne. We might add to the above definition of a compound leaf, that leaflets are jointed to the stalk, while the divisions called lobes never are. Such a statement would save trouble at first, but it would make greater trouble in the end. The truth is, that deeply-lobed leaves pass by insensible gradations into compound leaves, and compound leaves have their leaflets in all stages of connection with the common stalk, from a complete continuation of one into the other, up to a perfectly-jointed connection.

If the green matter of a leaf is continuous around the veins and along the ribs, however narrow the strip may be, it is quite correct to call such a specimen a simple leaf.

FIG. 90.

Lobes.

FIG. 91.

Leaflets.

There is no way, for the pupil, out of this difficulty except through a course of careful observation. Doubtless many mistakes will be made; but mistakes are very useful in education.