FRUIT, in its popular sense is any product of the soil that can be enjoyed by man or animals; in the Bible the word is often extended to include the offspring of man and of animals, e.g., in such expressions as "the fruit of the womb," "fruit of thy cattle" (Deut. xxviii. 4). More often it is employed to denote a group of edible parts of plants, as contrasted with another group termed "vegetable." But the term is a loose one, including, e.g., the stalks of the rhubarb.
In its strict botanical sense the fruit is developed from the flower as a result of fertilization of the ovule. This phenome non induces various changes: the anther and stigma wither, the petals drop off and the sepals may be shed or undergo modifi cations ; the ovary enlarges to form the pericarp and the ovules develop into the seeds, containing the embryo-plant. The term fruit is strictly applied only to the mature pistil or ovary, but it often includes other parts of the flower. Normally no fruit is produced unless fertilization is effected; but in certain plants, mostly cultivated varieties, this is not the case (e.g., the seedless oranges and grapes, the banana and the bread-fruit).
The fruit protects the growing and aids in distributing the mature seeds. This latter function is very important and numerous devices secure a wide and effective dis persal. These may be classified according to the agents employed as animate and inanimate. To the second group belong also those methods by which the plant itself propels the seed forcibly from the fruit. Some plants employ a combination of the two. Thus in the gorse the seeds are shot out by the splitting and curling of the pod in which they are contained, and they must then be buried by ants in order to germinate. Violent dehiscence occurs in many plants (fig. 28). In the squirting cucumber the walls of the pericarp exert pressure on the pulpy contents in which the seeds are placed. In the balsam (Impatiens) also the seeds are actively expelled. Other inanimate agents are water and wind. Fruits or seeds are sometimes sufficiently buoyant to float for a long time in water. Thus the coconut may be carried hundreds of miles in the sea; the fruits and seeds of West Indian plants are sometimes thrown up by the Gulf Stream on the coasts of Europe and will often germinate; in the water lily and many other aquatic plants, the seeds float for a time before sink ing to the bottom. In many cases the wind plays a part in distribution. In the poppy and many Caryophyllaceae (figs. 6, 7) there is a capsule opening by pores borne on a long stalk which sways in the wind, thus jerking out the seeds. In the pine, syca more (fig. 22), ash (fig. I) and many others, there is a wing-like development; in numerous Compositae the fruit is crowned by 'a plumose pappus (e.g., dandelion, thistle) ; in the clematis, the style becomes feathery, while the seeds of the willow and poplar bear tufts of silky hairs. The fruit of the bladder-senna (Colutea) is easily rolled by the wind, while in the Rose of Jericho (Ana statica hierochuntina), the whole plant dries up after developing its fruits and forms a mass, easily rolled over the dry ground by the wind.
Birds and mammals are also utilized as dispersal agents by plants. The mistletoe develops a sticky layer round the seeds which stick to the bill of the bird that eats the berries; these may be wiped off on the bark of trees, thus transporting the embryo to a new host. More commonly, the fruit develops hooks which become entangled in the fur or feathers. Such are the fruits of cleavers (Galiunn aparine), Ranunculus arvensis (fig. 2I ), etc. Another method is to provide the seed with a hard covering, while surrounding this with a succulent and often brightly col oured integument ; thus the seed can pass through the alimentary tract of an animal without injury, e.g., plum, cherry (fig. 5) ; or providing the true fruit with stiff hairs, which cling to the beak of the bird which eats the fleshy receptacle, e.g., rose (fig. 3).
Fruits may be divided into two groups. "A" consists of true fruits, developed from the ovary alone. Of these (I) consists of those in which the surrounding pericarp, round the seed, is not fleshy or fibrous. These again may be subdivided, (i.) Indehiscent fruits, not opening to allow the escape of the seeds. Such are generally one-seeded. The achene has the pericarp closely applied to the seeds, though sepa rable from it. Achenes are borne singly in the dock; aggregated together in the buttercup (fig. 21) ; on a fleshy receptacle, which may be convex as in the strawberry (fig. 2) or concave, as in the rose (fig. 3). Thus what is popularly called the fruit of these last three is really the swollen receptacle with the carpels. In Clematis the style, and many Compositae (in which the fruit is often called a cypsela) the modified calyx remains adherent to the fruit. A caryopsis differs from an achene in that the pericarp and seed become fused; wheat and grasses generally show this type of fruit. A nut possesses a hardened pericarp, often sur rounded by bracts at the base, and containing, when mature, a single seed. Examples are the hazelnut and the acorn (fig. 27). Achenes, in which the pericarp is extended to form a winged appendage, as in the ash (fig. I) and sycamore (fig. 22) are often called samaras. Those fruits which break into two or more one-seeded, indehiscent portions (mericarps) are termed schizocarps. Examples are found in the Geraniaceae, in which the mericarps separate from below upwards, in the Euphorbiaceae, etc. (ii) Dehiscent fruits, in which the pericarp splits to allow the escape of the seeds. They are generally many-seeded. When such a fruit dehisces by the ventral or, occasionally (Magnolia) by the dorsal, suture, it is called a follicle. There are usually several aggregated together; e.g., columbine (figs. 28, 29). A legume or pod differs in dehiscing by both sutures. This is char acteristic of leguminous plants, such as the pea (fig. 8). In Arachis the fruit does not dehisce, being produced under-ground. Hedysarum and others have a pod that separates transversely into single-seeded mericarps (fig. 18) ; such a structure is called a lomenturn and must be looked upon as a modified legume which no longer dehisces. In Erythrin a monosperma there is only one seed. In the Cruciferae (wallflower, cabbage, shepherd's purse), the characteristic fruit is a siliqua (fig. 34), which is long and narrow, or short and broad, silicula. In both of these there are two carpels, dehiscing by two valves from below upwards, the valves separating from the placentas and leaving them united by a false septum. As in the legume, single-seeded and lomenta ceous modifications are found. It is a development of the type of fruit known as a capsule, which is exhibited by the iris (fig. 12) . Capsules which open by pores (porose) are seen in the poppy (fig. 7) and Campanula. A pyxidium is a capsule opening by a lid, as in the pimpernel (fig. 17). Another type of capsule is exhibited by the Geraniaceae (fig. 19). (2) Fruits in which the pericarp is differentiated into distinct layers, one of which is succulent or fibrous. To this group belong many of the edible fruits. In the drupe, as shown by the cherry (fig. 5), plum, etc., the endo carp is usually hard and the mesocarp pulpy and succulent, though in the almond it is tough and in the coconut fibrous, In the raspberry and bramble several small drupes are aggre gated into an etaerio. The berry includes various types of fruit, all characterized by the fact that the seeds are immersed in pulp. To this group belong the barberry, gooseberry (fig. 3o), currant and pomegranate.
"B."—Fruits which include parts other than the ovary. These are called pseudocarps or false fruits. The fleshy, indehiscent pome of the apple (fig. 31), hawthorn, etc., incorporates the recep tacle, which becomes much swollen. The true fruit is the core. Superficially the pome resembles the "hip" of the rose. The fruits of the pineapple (sorosis) and fig (fig. 4) are compound pseudocarps, i.e., are formed from a number of flowers. In the pineapple, the fruit called a sorus is formed by the coalescence of a spike of flowers, as is also the case in the mulberry. In the fig, the whole inflorescence is a hollow structure bearing male and female flowers in the cavity ; each female flower forms a single true fruit. (See ANGIOSPERMS; FLOWER; SEED.)
