nation. It ends with death—that is, when no life is left in any part of the plant, and only the seed or spore remains to perpetuate the kind. In a bulbous plant, as a lily or an onion, the generation does not end until the bulb dies, even though the top is dead.
When the generation is of only one season's duration, the plant is said to be annual. When it is of two seasons, it is biennial. Biennials usually bloom the second year. When of three or more seasons, the plant is perennial. Examples of annuals are pigweed, bean, pea, garden sunflower; of biennials, evening primrose, mullein, teasel; of perennials, dock, most meadow grasses, cat-tail, and all shrubs and trees.
Duration of the Plant Body.—Plant structures which are more or less soft and which die at the close of the season are said to be herbaceous, in contradistinction to being ligneous or woody. A plant which is herbaceous to the ground is called an herb; but an herb may have a woody or perennial root, in which case it is called an herbaceous perennial. Annual plants are classed as herbs. Examples of herbaceous perennials are buttercups, bleeding heart, violet, water lily, Bermuda grass, horse-radish, dock, dandelion, golden rod, asparagus, rhubarb, many wild sunflowers (Figs. 11, 12).
Many herbaceous perennials have short generations. They become weak with one or two seasons of flowering and gradually die out. Thus, red clover usually begins to fail after the second year. Gardeners know that the best bloom of hollyhock, larkspur, pink, and many other plants, is secured when the plants are only two or three years old.
Herbaceous perennials which die away each season to bulbs or tubers, are sometimes called pseud-annuals (that
