The Elements of Botany Part 18

349. In respect to texture or consistence, fruits may be distinguished into three kinds, viz.--

_Fleshy Fruits_, those which are more or less soft and juicy throughout;

_Stone Fruits_, or _Drupaceous_, the outer part fleshy like a berry, the inner hard or stony, like a nut; and

_Dry Fruits_, those which have no flesh or pulp.

350. In reference to the way of disseminating the contained seed, fruits are said to be

_Indehiscent_ when they do not open at maturity. Fleshy fruits and stone fruits are of course indehiscent. The seed becomes free only through decay or by being fed upon by animals. Those which escape digestion are thus disseminated by the latter. Of dry fruits many are indehiscent; and these are variously arranged to be transported by animals. Some burst irregularly; many are

_Dehiscent_, that is, they split open regularly along certain lines, and discharge the seeds. A dehiscent fruit almost always contains many or several seeds, or at least more than one seed.

[Ill.u.s.tration: Fig. 371. Leafy shoot and berry (cut across) of the larger Cranberry, Vaccinium macrocarpon.]

[Ill.u.s.tration: Fig. 372, 373. Pepo of Gourd, in section. 373. One carpel of same in diagram.]

[Ill.u.s.tration: Fig. 374. Longitudinal and transverse sections of a pear (pome).]

351. The princ.i.p.al kinds of fruit which have received substantive names and are of common use in descriptive botany are the following. Of fleshy fruits the leading kind is

352. =The Berry=, such as the gooseberry and currant, the blueberry and cranberry (Fig. 371), the tomato, and the grape. Here the whole flesh is soft throughout. The orange is a berry with a leathery rind.

353. =The Pepo=, or _Gourd-fruit_, is a hard-rinded berry, belonging to the Gourd family, such as the pumpkin, squash, cuc.u.mber, and melon, Fig.

372, 373.

354. =The Pome= is a name applied to the apple, pear (Fig. 374), and quince; fleshy fruits, like a berry, but the princ.i.p.al thickness is calyx, only the papery pods arranged like a star in the core really belonging to the carpels. The fruit of the Hawthorn is a drupaceous pome, something between pome and drupe.

355. Of fruits which are externally fleshy and internally hard the leading kind is

356. =The Drupe=, or _Stone-fruit_; of which the cherry, plum, and peach (Fig. 375) are familiar examples. In this the outer part of the thickness of the pericarp becomes fleshy, or softens like a berry, while the inner hardens, like a nut. From the way in which the pistil is constructed, it is evident that the fleshy part here answers to the lower, and the stone to the upper face of the component leaf. The layers or concentric portions of a drupe, or of any pericarp which is thus separable, are named, when thus distinguishable into three portions,--

_Epicarp_, the external layer, often the mere skin of the fruit,

_Mesocarp_, the middle layer, which is commonly the fleshy part, and

_Endocarp_, the innermost layer, the stone. But more commonly only two portions of a drupe are distinguished, and are named, the outer one

_Sarcocarp_ or _Exocarp_, for the flesh, the first name referring to the fleshy character, the second to its being an external layer; and

_Putamen_ or _Endocarp_, the _Stone_, within.

[Ill.u.s.tration: Fig. 375. Longitudinal section of a peach, showing flesh, stone, and seed.]

357. The typical or true drupe is of a single carpel. But, not to multiply technical names, this name is extended to all such fruits when fleshy without and stony within, although of compound pistil,--even to those having several or separable stones, such as the fruit of Holly.

These stones in such drupes, or drupaceous fruits, are called _Pyrenae_, or _Nucules_, or simply _Nutlets_ of the drupe.

358. Of Dry fruits, there is a greater diversity of kinds having distinct names. The indehiscent sorts are commonly one-seeded.

[Ill.u.s.tration: Fig. 376. Akene of a b.u.t.tercup. 377. The same, divided lengthwise, to show the contained seed.]

[Ill.u.s.tration: Fig. 378. Akene of Virgin's-bower, retaining the feathered style, which aids in dissemination.]

359. =The Akene or Achenium= is a small, dry and indehiscent one-seeded fruit, often so seed-like in appearance that it is popularly taken for a naked seed. The fruit of the b.u.t.tercup or Crowfoot is a good example, Fig. 376, 377. Its nature, as a ripened pistil (in this case a simple carpel), is apparent by its bearing the remains of a style or stigma, or a scar from which this has fallen. It may retain the style and use it in various ways for dissemination (Fig. 378).

360. The fruit of Compositae (though not of a single carpel) is also an akene. In this case the pericarp is invested by an adherent calyx-tube; the limb of which, when it has any, is called the PAPPUS. This name was first given to the down like that of the Thistle, but is applied to all forms under which the limb of the calyx of the "compound flower"

appears. In Lettuce, Dandelion (Fig. 384), and the like, the achenium as it matures tapers upwards into a slender beak, like a stalk to the pappus.

[Ill.u.s.tration: Fig. 379. Akene of Mayweed (no pappus). 380. That of Succory (its pappus a shallow cup). 381. Of Sunflower (pappus of two deciduous scales). 382. Of Sneezeweed (Helenium), with its pappus of five scales. 383. Of Sow-Thistle, with its pappus of delicate downy hairs. 384. Of the Dandelion, its pappus raised on a long beak.]

361. =A Cremocarp= (Fig. 385), a name given to the fruit of Umbelliferae, consists as it were of a pair of akenes united completely in the blossom, but splitting apart when ripe into the two closed carpels. Each of these is a _Mericarp_ or _Hemicarp_, names seldom used.

362. =A Utricle= is the same as an akene, but with a thin and bladdery loose pericarp; like that of the Goosefoot or Pigweed (Fig. 386). When ripe it may burst open irregularly to discharge the seed; or it may open by a circular line all round, the upper part falling off like a lid; as in the Amaranth (Fig. 387).

[Ill.u.s.tration: Fig. 385. Fruit (cremocarp) of Osmorrhiza; the two akene-like ripe carpels separating at maturity from a slender axis or carpoph.o.r.e.]

[Ill.u.s.tration: Fig. 386. Utricle of the common Pigweed (Chenopodium alb.u.m).]

[Ill.u.s.tration: Fig. 387. Utricle (pyxis) of Amaranth, opening all round (circ.u.mscissile).]

363. =A Caryopsis, or Grain=, is like an akene with the seed adhering to the thin pericarp throughout, so that fruit and seed are incorporated into one body; as in wheat, Indian corn, and other kinds of grain.

364. =A Nut= is a dry and indehiscent fruit, commonly one-celled and one-seeded, with a hard, crustaceous, or bony wall, such as the cocoa-nut, hazelnut, chestnut, and the acorn (Fig. 37, 388.) Here the involucre, in the form of a cup at the base, is called the CUPULE. In the Chestnut the cupule forms the bur; in the Hazel, a leafy husk.

[Ill.u.s.tration: Fig. 388. Nut (acorn) of the Oak, with its cup or cupule.]

365. =A Samara, or Key-fruit=, is either a nut or an akene, or any other indehiscent fruit, furnished with a wing, like that of Ash (Fig. 389), and Elm (Fig. 390). The Maple-fruit is a pair of keys (Fig. 391).

366. Dehiscent Fruits, or Pods, are of two cla.s.ses, viz., those of a simple pistil or carpel, and those of a compound pistil. Two common sorts of the first are named as follows:--

367. =The Follicle= is a fruit of a simple carpel, which dehisces down one side only, i. e. by the inner or ventral suture. The fruits of Marsh Marigold (Fig. 392), Paeony, Larkspur, and Milkweed are of this kind.

[Ill.u.s.tration: Fig. 389. Samara or key of the White Ash, winged at end.

390. Samara of the American Elm, winged all round.]

[Ill.u.s.tration: Fig. 391. Pair of samaras of Sugar Maple.]

[Ill.u.s.tration: Fig. 392. Follicle of Marsh Marigold (Caltha pal.u.s.tris).]

[Ill.u.s.tration: Fig. 393. Legume of a Sweet Pea, opened.]

[Ill.u.s.tration: Fig. 394. Loment or jointed legume of a Tick-Trefoil (Desmodium).]

368. =The Legume= or true Pod, such as the peapod (Fig. 393), and the fruit of the Leguminous or Pulse family generally, is one which opens along the dorsal as well as the ventral suture. The two pieces into which it splits are called VALVES. A LOMENT is a legume which is constricted between the seeds, and at length breaks up crosswise into distinct joints, as in Fig. 394.

369. The pods or dehiscent fruits belonging to a compound ovary have several technical names: but they all may be regarded as kinds of

370. =The Capsule=, the dry and dehiscent fruit of any compound pistil.

The capsule may discharge its seeds through c.h.i.n.ks or pores, as in the Poppy, or burst irregularly in some part, as in Lobelia and the Snapdragon; but commonly it splits open (or is _dehiscent_) lengthwise into regular pieces, called VALVES.