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what altered in form and colour; the stamens are leaves, of which the petioles are represented by the filaments, while the expanded portion, being turned inwards upon the midrib, becomes the anther; the carpels of the pistil are likewise leaves variously modified. This interesting fact, long since surmised by Goethe, has been long verified by accurate observation; and some of its results are of importance even to the non-scientific observer of flowers. Occasionally portions of the corolla are found developed as green leaves,—a monstrosity frequently occurring in the garden Tulip. The flowers called double are produced by a similar metamorphosis, the leaves that are usually developed as stamens and pistils assuming the petaloid form; hence perfectly double flowers are incapable of maturing seed.
The duration of plants is variable in different species; but the general process of growth is the same in all. The seed, lying upon the ground, germinates under the influence of heat and moisture; the radicle is elongated, and, penetrating the soil, pushes forth fibres which draw up nutriment for the support of the growing plant; the plumule rises, bearing with it the cotyledons, which acquire the green colour of leaves, and are soon succeeded by the true leaves. At some period of its growth the leaves are developed in forms more or less modified, and become no longer organs of respiration and transpiration, but assume the characters of floral envelopes and of stamens and pistils, through the mutual action of which the seed is produced.
Some plants spring up from the seed and bear flowers and fruit within a single season, dying when the process is completed—or are annual. Others produce no flowers the first year, but store up during that period of growth the nutriment which is absorbed in the production of seed in the following summer, when they die; these are called biennial. When the plant survives for an indefinite period it becomes perennial, either throwing up stems from the root each year, which die down after bearing flowers, or producing a
