CHAPTER XXI
FRUITS
The ripened ovary, with its attachments, is known as the fruit. It contains the seeds. If the pistil is simple, or of one carpel, the fruit also will have one compartment. If the pistil is compound, or of more than one carpel, the fruit usually has an equal number of compartments. The compartments in pistil and fruit are known as locules (from Latin locus, meaning “a place”).
Fig. 224.—Dentaria, or Tooth-wort, in fruit.
The simplest kind of fruit is a ripened 1-loculed ovary. The first stage in complexity is a ripened 2- or many-loculed ovary. Very complex forms may arise by the attachment of other parts to the ovary. Sometimes the style persists and becomes a beak (mustard pods, dentaria, Fig. [224]), or a tail as in clematis; or the calyx may be attached to the ovary; or the ovary may be embedded in the receptacle, and ovary and receptacle together constitute the fruit: or an involucre may become a part of the fruit, as possibly in the walnut and the hickory (Fig. [225]), and the cup of the acorn (Fig. [226]). The chestnut and the beech bear a prickly involucre, but the nuts, or true fruits, are not grown fast to it, and the involucre can scarcely be called a part of the fruit. A ripened ovary is a pericarp. A pericarp to which other parts adhere has been called an accessory or reënforced fruit. (Page 169.)
Fig. 225.—Hickory-nut. The nut is the fruit, contained in a husk.
Fig. 226.—Live-oak Acorn. The fruit is the “seed” part; the involucre is the “cup.”
Some fruits are dehiscent, or split open at maturity and liberate the seeds; others are indehiscent, or do not open. A dehiscent pericarp is called a pod. The parts into which such a pod breaks or splits are known as valves. In indehiscent fruits the seed is liberated by the decay of the envelope, or by the rupturing of the envelope by the germinating seed. Indehiscent winged pericarps are known as samaras or key fruits. Maple (Fig. [227]), elm (Fig. [228]), and ash (Fig. [93]) are examples.