Page:Encyclopædia Britannica, Ninth Edition, v. 4.djvu/163

FORMS OF FRUIT.] BOTANY 153 is called siliqua (fig. 304) ; when broad and short, it is called silicula (figs. 305, 306). It occurs in Cruciferous plants, as Wallflower, Cabbage, and Cress. In Glaucium and lute II. Eschscholtzia (Papaveraceous plants) tho fruit is siliquse- 9 - form, the dissepiment or replum being of a spongy nature, and it has been termed a ceratium. In its normal state a siliqua is supposed to consist of four carpels, but two of these arc abortive. There are four bundles of vessels in it, one corresponding to each valve which may be called valvular or pericarpial, and others running along the edge called placental. The replum consists of two lamellse. It some times exhibits perforations, becoming fenestrate. Rarely its central portion is absorbed, so that the fruit becomes one-celled. It may become lomentaceous, as in Raphanus and Sea-kale, and it may be reduced, as in Woad (Isatis), to a monospermal condition. It sometimes happens that the ovaries of two flowers unite so as to form a double fruit. This may be seen in many species of Honeysuckle. But tho fruits which are now to be considered consist usually of the floral envelopes, as well as the ovaries of several flowers united into one, and are called multiple, confluent, or polygynoecial. The term anthocarpous has also been applied as indicating that the floral envelopes as well as the carpels are concerned in the formation of the fruit. The sorosis is a succulent multiple fruit formed by the confluence of a spike of flowers, as in the fruit of the late XIV. Pine-applo (fig. 307), the Bread-fruit, and Jack-fruit. Sometimes a fruit of this kind resembles that formed by a single flower, and a superficial observer might have some difficulty in marking the differenco. The syconus is an anthocarpous fruit, in which the recep tacle completely encloses .numerous flowers and becomes suc culent. The Fig (fig. 150) is of this nature, and what are called its seeds are the achasnia of the numerous flowers scattered over tho succulent hollowed receptacle. In Dorstenia (fig. 1G3) the axis is less deeply hollowed, and of a harder texture, the fruit exhibiting often very anomalous forms. The strobilus, or cone, is a fruit-bearing spike, more or less elongated, covered with scales (fig. 134), each of which represents a separate flower, and has often two seeds at its base, the scales being considered as bracts and the seeds naked, and no true ovary present with its style or stigma. This fruit is seen in the cones of Firs, Spruces, Larches, and Cedars, which have received the name of Coniferse, or cone-bearers, on this account. Cone-like fruit is also seen in some Cycadacere. Tho scales of the strobilus are some times ; thick and closely united, so as to form a more or less angular and rounded mass, as in the Cypress ; while in tho Juniper they become fleshy, and are so incorporated as to form a globular fruit, like a berry. The dry fruit of the Cypress, and the succulent fruit of the Juniper, have received the name of galbulus. The fruit of the Yew (Taxus baccata) is regarded as a cone reduced to a single naked seed, covered by succulent scales, which unite to form a scarlet fleshy envelope. In the Hop the fruit is called also a strobilus, but in it the scales are thin and membranous, and the seeds are not naked but are contained in pericarps. The same causes which produce alterations in the other parts of the flower give rise to anomalous appearances in the fruit. The carpels, in place of bearing seeds, are some times changed into leaves, with lobes at their margins. Leaves are sometimes produced from the upper part of the fruit, which is then called frondiparous. In the genus Citrus, to which the Orange and Lemon belong, it is very common to meet with a separation of tho carpels, so as to produce what arc called horned oranges and fingered citrons. In this case a syncarpous fruit has a tendency to become apocarpous. In the Orange we occasionally find a supernumerary row of carpels produced, giving rise to tho appearance of small and imperfect oranges enclosed within the original one. The Navel Orange of Pernambuco is of this nature. It sometimes happens that, by the union of flowers, double fruits are produced. Occasionally a double fruit is produced, not by the incorporation of two flowers, but by the abnormal development of a second carpel in the flower. ARRANGEMENT OF FRUITS. I. Monogynoecial fruits, formed by the gynoecium of one flower. 1. Capsulary fruits. Dry, dehiscent, formed by one or more carpels ; when by more than one, coherent. a. Monocarpellary. Legume ; Follicle. 1. Polycarpellary. Capsule ; Fyxidium ; Siliqua ; Silicula ; Ceratium ; Diplotegia ; Eegma. 2. Aggregate fruits. Polycarpellary ; carpels always distinct. a. Indehiscent. Etaerio ; Strawberry ; Cynarrhodum. b. Dehiscent. Follicles (Columbine). 3. Schizocarpic fruits. Dry, breaking up into one-celled inde- hiscent portions. a. Monocarpellary. Lorn en turn. b. Polycarpellary. Cremocarp; Carcerulus; Samara (Acer). 4. Achcenial fruits. Dry, indehiscent, one or few-seeded, not breaking up. Achamium ; Caryopsis ; Utricle ; Samara (Elm) ; Cypsela ; Glans. 5. Baccate fruits. Indehiscent ; seeds in pulp. Bacca ; Uva ; Hesperidium ; Pepo ; Amphisarca ; Balausta. 6. Drupaceous fruits. Indehiscent, succulent, endocarp in durated, usually stony. Drupe ; Tryma ; Pome ; Nucu- lanium. II. Polygyncecial fruits, formed by the gyncecia of several flowers. 1. Succulent. Sorosis; Syconus; Galbulus. 2. Dry. Strobilus ; Cone. ?>. The Seed. When the ovule arrives at maturity it constitutes the seed, TLe seed, which is contained in a seed-vessel in the plants called angio- spermous ; while in gymnospermous plants, such as Conifers and Cycadacese, it is naked, or, in other words, has no true pericarp. It sometimes happens in angiosperms, that the seed-vessel is ruptured at an early period of growth, so that the seeds become more or less exposed during their de velopment ; this occurs in Mignonette, where the capsule opens at the apex, and in Cuphea platycentra, where tho placenta bursts through the ovary and floral envelopes, and appears as an erect process bearing the young seeds. After impregnation the ovule is greatly changed, in con nection wirh the formation of the embryo. In the embryo- sac of most angiosperms there is a development of cellular tissue, enveloping, when not previously absorbed, tho anti podal cells, and more or less filling the embryo sac. In gymnosperms, as already mentioned, the endosperm is formed preparatory to fertilization. The germinal vesicle in angiosperms, the central cell of the corpuscle in crypto gams, enlarges and divides, forming the embryo. The em bryo-sac enlarges greatly, displacing gradually the nucleus, which may eventually form merely a thin layer around the sac, or it may completely disappear. The integuments also become much altered, and frequently appendages are developed from them. The general integumentary covering of the seed is called spermoderm. In it are recognized two parts, an external membrane, called the episperm or testa (fig. 308, te), and an internal membrane, called endoplcura or tegmen, e, which however is often incorporated with the testa, and hardly separable from it. The testa may consist of a union of tho primine and secundine, or of the primine only, when, as occasionally happens, the secundine is absorbed ; the endopleura, of a combination between the outer layer of the nucleus (sometimes termed tho tercine), and the embryo- sac, or of one of these parts alone. Sometimes the secundine remains distinct in the seed, forming what has been called a mcsn,<:):erm ; and when it assumes a fleshy

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