SUGGESTIONS.--=8.= The teacher may assign each pupil to one plant in
the school yard, or field, or in a pot, and ask him to bring out the
points in the lesson. =9.= The teacher may put on the board the names
of many common plants and ask the pupils to classify into annuals,
pseud-annuals, plur-annuals (or climatic annuals), biennials,
perennials, herbaceous perennials, ligneous perennials, herbs,
bushes, trees. Every plant grown on the farm should be so classified:
wheat, oats, corn, buckwheat, timothy, strawberry, raspberry,
currant, tobacco, alfalfa, flax, crimson clover, hops, cowpea, field
bean, sweet potato, peanut, radish, sugar-cane, barley, cabbage, and
others. Name all the kinds of trees you know.
CHAPTER VI
SEEDS AND GERMINATION
[Illustration: FIG. 15.--PARTS OF THE BEAN.
_R_, cotyledon; _O_, caulicle; _A_, plumule; _F_, first node.]
The seed contains a _miniature plant_, or =embryo=. The embryo usually
has three parts that have received names: the stemlet, or =caulicle=;
the seed-leaf, or =cotyledon= (usually 1 or 2); the bud, or =plumule=,
lying between or above the cotyledons. These parts are well seen in the
common bean (Fig. 15), particularly when the seed has been soaked for a
few hours. One of the large cotyledons--comprising half of the bean--is
shown at _R_. The caulicle is at _O_. The plumule is shown at _A_. The
cotyledons are attached to the caulicle at _F_: _this point may be
taken as the first node or joint_.
=The Number of Seed-leaves.=--All plants having _two seed-leaves_
belong to the group called =dicotyledons=. Such seeds in many
cases split readily in halves, _e.g._ a bean. Some plants have
only _one_ seed-leaf in a seed. They form a group of plants called
=monocotyledons=. Indian corn is an example of a plant with only one
seed-leaf: a grain of corn does not split into halves as a bean does.
Seeds of the pine family contain more than two cotyledons, but for our
purposes they may be associated with the dicotyledons, although really
forming a different group.
These two groups--the dicotyledons and the monocotyledons--represent
two great natural divisions of the vegetable kingdom. The dicotyledons
contain the woody bark-bearing trees and bushes (except conifers), and
most of the herbs of temperate climates except the grasses, sedges,
rushes, lily tribes, and orchids. The flower-parts are usually in fives
or multiples of five, the leaves mostly netted-veined, the bark or
rind distinct, and the stem often bearing a pith at the center. The
monocotyledons usually have the flower-parts in threes or multiples of
three, the leaves long and parallel-veined, the bark not separable, and
the stem without a central pith.
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