GRAPE BOTANY
The grape-grower must know the gross structure and the habits of growth of the plants properly to propagate, transplant, prune and otherwise care for the grape. Certainly he must have knowledge of the several species from which varieties come if he is to know the kinds of grapes, understand their adaptations to soils and climates, their relation to insects and fungi, and their value for table, wine, grape-juice and other purposes. Fortunately, the botany of the grape is comparatively simple. The organs of vine and fruit are distinctive and easily discerned and there are no nearly related plants cultivated for fruit with which the grape can possibly be confused. Botanists, it is true, have dug pitfalls for those who seek exact knowledge as to the names and characters of the many species, but, fortunately, each of the cultivated species constitutes a natural group so distinct that the grape-grower can hardly mistake one for another in either fruit or vine.
Plant Characters and Growth Habits of the Grape
A grape plant is a complex organism with its many separate parts especially developed to do one or a few kinds of work. The part of a plant devoted to one or a group of functions is called an organ. The chief organs of the plant are the root, stem, bud, flower, leaf, fruit and seed. Flowers and leaves, it is true, develop from buds and the seeds are parts of the fruits, but for descriptive purposes the vine may well be divided into the parts named. These chief organs are further divided as follows:
The root.
- Root-crown: The region of the plant in which root and stem unite.
- Tap-root: The prolongation of the stem plunging vertically downward.
- Rootlets: The ultimate divisions of the root; usually of one season's growth.
- Root-tips: The extreme ends of the rootlets.
The roots of some species of the grape are soft and succulent as those of V. vinifera, while the same organs in other species, as in most American grapes, are hard and fibrous. They may also be few or numerous, deep or shallow, spreading or restricted, fibrous or non-fibrous. The structure of the root thus becomes important in distinguishing species.
The stem.
- Stem or trunk: The unbranched main axis of the plant above ground.
- Branches or arms: Main divisions of the trunk.
- Head: The region from which branches arise.
- Old wood: Parts of the vine older than one year.
- Canes: Wood of the current season.
- Spurs: Short pieces of the bases of canes; usually one or two nodes with a bud each.
- Renewal spurs: Spurs left to bear canes the following year.
- Shoots: Newly developed succulent stems with their leaves.
- Fruit-shoots: Flower and fruit-bearing shoots.
- Wood-shoots: Shoots which bear leaves only.
- Laterals: Secondary shoots arising from main shoots.
- Water sprouts: Shoots arising from adventitious buds.
- Suckers: Shoots arising from below ground.
- Nodes: Joints in the stem from which leaves are or may be borne.
- Internodes: The part between two nodes.
- Diaphragm: The woody tissue which interrupts the pith at the node.
- Bloom: The powdery coating on the cane.
- Tendril: The coiled, thread-like organ by which the vine grasps an object and clings to it.
Species of grapes have very characteristic vines. A glance at a vine enables one to tell the European grape from any of the American grapes; so, also, one is able to distinguish most of the American species by the aspect of the vine. Many varieties of any species of grape are readily told by the size and habits of the plant. Size of vine is rather more variable than other gross characters because of the influence of environment, such as food, moisture, light, isolation and pests; yet, size in a plant or the parts of a plant is a very reliable character when proper allowances are made for environment.