Herbaceous perennials which die away each season to bulbs or tubers, are sometimes called pseud-annuals (that is, false annuals). Of such are lily, crocus, onion, potato, and bull nettle.
True annuals reach old age the first year. Plants which are normally perennial may become annual in a shorter-season climate by being killed by frost, rather than by dying naturally at the end of a season of growth. They are climatic annuals. Such plants are called plur-annuals in the short-season region. Many tropical perennials are plur-annuals when grown in the north, but they are treated as true annuals because they ripen sufficient of their crop the same season in which the seeds are sown to make them worth cultivating, as tomato, red pepper, castor bean, cotton. Name several vegetables that are planted in gardens with the expectation that they will bear till frost comes.
Fig. 13.—A Shrub or Bush. Dogwood osier.
Woody or ligneous plants usually live longer than herbs. Those that remain low and produce several or many similar shoots from the base are called shrubs, as lilac, rose, elder, osier (Fig. [13]). Low and thick shrubs are bushes. Plants that produce one main trunk and a more or less elevated head are trees (Fig. [14]). All shrubs and trees are perennial.
Every plant makes an effort to propagate, or to perpetuate its kind; and, as far as we can see, this is the end for which the plant itself lives. The seed or spore is the final product of the plant.
Fig. 14.—A Tree. The weeping birch.
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.