=The Stem Part.=--In most plants there is a _main central part or shaft_ on which the other or _secondary parts_ are borne. This main part is the =plant axis=. Above ground, in most plants, the main plant axis bears the _branches_, _leaves_, and _flowers_; below ground, it bears the _roots_. The rigid part of the plant, which persists over winter and which is left after leaves and flowers are fallen, is the =framework= of the plant. The framework is composed of both root and stem. When the plant is dead, the framework remains for a time, but it slowly decays. The dry winter stems of weeds are the framework, or skeleton of the plant (Figs. 11 and 12). The framework of trees is the most conspicuous part of the plant. =The Root Part.=--The root bears the stem at its apex, but otherwise it normally _bears only root-branches_. The stem, however, _bears leaves_, _flowers_, _and fruits_. Those living surfaces of the plant which are most exposed to light are _green or highly colored_. The root tends to grow _downward_, but the stem tends to grow _upward toward light and air_. The plant is anchored or fixed in the soil by the roots. Plants have been called “earth parasites.” =The Foliage Part.=--The _leaves precede the flowers_ in point of time or life of the plant. _The flowers always precede the fruits and seeds._ Many plants die when the seeds have matured. The whole mass of leaves of any plant or any branch is known as its _foliage_. In some cases, as in crocuses, the flowers seem to precede the leaves; but the leaves that made the food for these flowers grew the preceding year. [Illustration: FIG. 11.--PLANT OF A WILD SUNFLOWER.] [Illustration: FIG. 12.--FRAMEWORK OF FIG. 11.] =The Plant Generation.=--The course of a plant’s life, with all the events through which the plant naturally passes, is known as the plant’s =life-history=. The life-history embraces various stages, or epochs, as _dormant seed_, _germination_, _growth_, _flowering_, _fruiting_. Some plants run their course in a few weeks or months, and some live for centuries. The entire life-period of a plant is called a =generation=. It is the whole period from birth to normal death, without reference to the various stages or events through which it passes. A generation begins with _the young seed_, not with germination. _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.