Page:The American Cyclopædia (1879) Volume XIII.djvu/607

 PLANT 591 but of the pericarp. Of the same structure with these conspicuous examples of the drupe is the very small drupe of the raspberry and blackberry ; in these each ovary becomes a minute stone fruit ; these as they grow are much crowded, and in the raspberry they co- here, but when mature they separate entirely from the receptacle, which has nourished them, as a little cap ; in the blackberry the little drupes retain their hold upon the receptacle, which becomes more or less juicy and edible. Berry is a general name for fleshy fruits, with- out reference to the number of carpels ; in the papaw the fruit is an elongated very pulpy ber- ry, resulting from a simple pistil ; in the grape the pistil has two carpels, and in the gooseberry and tomato three ; in the tomato cultivation has brought the fruit into an abnormal condition, and while its botanical structure is broken up and confused, it is much improved in an eco- nomical point of view, as the fleshiness in this belongs mainly to the placenta. A pepo is a berry with a hard rind, of which the squash, melon, and all of the gourd family are illustra- tions ; in the proper gourd the rind when ripe is very hard and woody, and the pulp dry ; in the watermelon and cucumber the rind never becomes very hard, while the pulp is very juicy. In the orange, lemon, and others of the family, the fruit results from a many-celled ovary ; when ripe it has a leathery and often very thick pericarp ; the cell walls remain and divide the fruit into sections, which are filled with separable cells containing a watery juice ; this kind of fruit is called a hesperidium. Of dehiscent fruits, or capsules resulting from a compound pistil, the crucifers or mustard family present a simple form; the mustard, cabbage, and others have the form called si- lique, in which the ovary consists of two car- pels and has two parietal placentae; the cap- sule usually falls apart in two valves, leaving the framework to which the seeds are attached. In the iris, the three carpels break open on the back (loculicidal dehiscence), while in the col- chicum the cells open at the ventral suture (septicidal). The poppy capsule liberates its seeds through a number of openings below the persistent stigma; in the common purslane of the gardens the capsule opens by a transverse fissure, the upper half falling away. In inde- hiscent fruits the pericarp sometimes decays to set free the seeds, and in other cases it is rup- tured by the swelling of the contained seed when it germinates. Among fruits formed by the aid of other parts than the ovary, the most common is the pome, of which the apple is a familiar illustration ; as in the flower of the apple the calyx is so united' with the ovary that it appears as if seated upon it, so in the fruit we find this union of calyx and ovary still continued ; in the apple the proper car- pels are the parchment-like bodies which are found at the core, and when the fruit is cut across appear arranged in a circle in the cen- tre, and enclosing the seeds ; these are imme- diately surrounded by a pulpy expansion of the receptacle, and outside of the whole is the enlarged succulent calyx tube which makes up the greater bulk of the fruit, its persistent free divisions generally remaining in a withered state when the apple is mature. In the aro- matic wintergreen or checkerberry, the edible portion of the fruit is the enlarged calyx, not in this case united with the ovary, which is a dry capsule loosely invested by the pulpy calyx. The grain (caryopsis), of which the cereals are examples, results from a one-seeded ovary, the seed usually adherent to the proper pericarp, which becomes very thin and papery, and is commonly known as the hull. Fruits which result from several distinct flowers closely crowded upon a common axis are aggregate fruits, of which the pineapple is a remarkable illustration. (See PINEAPPLE.) The mulberry shows a similar structure on a much smaller scale. In the pine family the pistil is an open carpellary leaf or scale, and the same struc- ture is retained in the fruit, where the scales enlarge and become woody, as in the pine and related genera (see PINE), or they become fleshy, as in the juniper and some others. The cashew (anacaraivm), a tropical tree, presents a most anomalous fruit, it being no part of the flower ; the pistil ripens into a nut, some- times found in commerce, the cashew nut, and at the same time the peduncle or flower stalk undergoes a change, swelling into a pear- shaped, pulpy, edible mass called the cashew apple, upon the top of which the nut rests. The Seed. The proper nourishment, maturing, protection, and final distribution of seeds are the ultimate object of all the varied forms of the fruit. The internal structure of dicotyle- donous seeds has been sufficiently described. Monocotyledonous seeds present an equal vari- ety in their structure and methods of germina- tion. In some cases the embryo is an elonga- ted cylindrical body, in which no distinction of parts is apparent until germination takes place ; the lower end of an embryo of this kind (e. g., onion) is the radicle, and the upper portion is a cotyledon, wrapped around a plumule, which shows itself when the seed germinates ; on the other hand, maize or Indian corn has a high- ly developed embryo, in which the radicle is distinct, bearing a single large cotyledon partly enveloping that and the plumule, which con- sists of several rudimentary leaves closely en- wrapping one another. In monocotyledonous plants the growth of the primary root soon ceases (see PALM), abundant secondary roots being formed from the lower nodes of the proper stem or axis, as may be seen in young plants of maize. The ovule has been de- scribed as having two coats; these when the embryo is ripe become the seed coats ; the in- ner, the tegmen, is sometimes manifest, but it is often united with the outer or wanting alto- gether. The outer seed coat, the testa, varies greatly, and it is due to the character and markings of this that seeds differ so greatly in