FIG. 18.--Fruit of _Geranium pratense_, after splitting.]_Encyclopaedia Britannica, 11th Edition, "Frost" to "Fyzabad" Volume 11, Slice 3

Sometimes the axis is prolonged beyond the base of the carpels, as in

the mallow and castor-oil plant, the carpels being united to it

throughout their length by their faces, and separating from it without

opening. In the Umbelliferae the two carpels separate from the lower

part of the axis, and remain attached by their apices to a

prolongation of it, called a _carpophore_ or _podocarp_, which splits

into two (fig. 25) and suspends them; hence the fruit is termed a

_cremocarp_, which divides into two _mericarps_. The general term

_schizocarp_ is applied to all dry fruits, which break up into two or

more one-seeded indehiscent mericarps, as in _Hedysarum_ (fig. 17). In

the order Geraniaceae the styles remain attached to a central column,

and the mericarps separate from below upwards, before dehiscing by

their ventral suture (fig. 18). Carpels which separate one from

another in this manner are called _cocci_. They are well seen in the

order Euphorbiaceae, where there are usually three such carpels, and

the fruit is termed tricoccus. In many of them, as _Hura crepitans_,

the cocci separate with great force and elasticity. In many leguminous

plants, such as _Ornithopus_, _Hedysarum_ (fig. 17), _Entada_,

_Coronilla_ and the gum-arabic plant (_Acacia arabica_), the fruit

becomes a schizocarp by the formation of transverse partitions from

the folding in of the sides of the pericarp, and distinct separations

taking place at these partitions.

Fruits are formed by one flower, or are the product of several flowers

combined. In the former case they are either _apocarpous_, of one

mature carpel or of several separate free carpels; or _syncarpous_, of

several carpels, more or less completely united. When the fruit is

composed of the ovaries of several flowers united, it is usual to find

the bracts and floral envelopes also joined with them, so as to form

one mass; hence such fruits are known as multiple, confluent or

_anthocarpous_. The term simple is applied to fruits which are formed

by the ovary of a single flower, whether they are composed of one or

several carpels, and whether these carpels are separate or combined.

[Illustration: From Vines' _Students' Text-Book of Botany_, by

permission of Swan Sonnenschein & Co.

FIG. 19.--Dry one-seeded fruit of dock (_Rumex_) cut vertically. ov,

Pericarp formed from ovary wall; s, seed; e, endosperm; pl, embryo

with radicle pointing upwards and cotyledons downwards--enlarged.

FIG. 20.--Achene of _Ranunculus arvensis_ in longitudinal section;

e, endosperm; pl, embryo. (After Baillon, enlarged.)

From Strasburger's _Lehrbuch der Botanik_, by permission of Gustav

Fischer.

FIG. 21.--Fruit of Common Sycamore (_Acer Pseudoplatanus_), dividing

into two mericarps m; s, pedicel; fl, wings (nat. size).]

Dispersal of fruit or seed.

The object of the fruit in the economy of the plant is the protection

and nursing of the developing seed and the dispersion of the ripe

seeds. Hence, generally, one-seeded fruits are indehiscent, while

fruits containing more than one seed open to allow of the dispersal of

the seeds over as wide an area as possible. The form, colour,

structure and method of dehiscence of fruits and the form of the

contained seeds are intimately associated with the means of dispersal,

which fall into several categories. (1) By a mechanism residing in the

fruit. Thus many fruits open suddenly when they are dry, and the seeds

are ejected by the twisting or curving of the valves, or in some other

way; e.g. in gorse, by the spiral curving of the valves; in

_Impatiens_, by the twisting of the cocci; in squirting cucumber, by

the pressure exerted on the pulpy contents by the walls of the

pericarp. (2) By aid of various external agencies such as water.

Fruits or seeds are sometimes sufficiently buoyant to float for a long

time on sea- or fresh-water; e.g. coco-nut, by means of its thick,

fibrous coat (mesocarp), is carried hundreds of miles in the sea, the

tough, leathery outer coat (epicarp) preventing it from becoming

water-soaked. Fruits and seeds of West Indian plants are thrown up on

the coasts of north-west Europe, having been carried by the Gulf

Stream, and will often germinate; many are rendered buoyant by

air-containing cavities, and the embryo is protected from the seawater

by the tough coat of fruit or seed. Water-lily seeds are surrounded

with a spongy tissue when set free from the fruit, and float for some

distance before dropping to the bottom. (3) The most general agent in

the dispersal of seeds is the wind or currents of air--the fruit or

seed being rendered buoyant by wing-developments as in fruits of ash

(fig. 1) or maple (fig. 21), seeds of pines and firs, or many members

of the order Bignoniaceae; or hair-developments as in fruits of

clematis, where the style forms a feathery appendage, fruits of many

Compositae (dandelion, thistle, &c.), which are crowned by a plumose

pappus, or seeds of willow and poplar, or _Asclepias_ (fig. 36), which

bear tufts of silky hairs; to this category belong bladder-like

fruits, such as bladder-senna, which are easily rolled by the wind, or

cases like the so-called rose of Jericho, a small cruciferous plant

(_Anastatica hierocuntica_), where the plant dries up after developing

its fruits and becomes detached from the ground; the branches curl

inwards, and the whole plant is rolled over the dry ground by the

wind. The wind also aids the dispersal of the seeds in the case of

fruits which open by small teeth (many Caryophyllaceae [fig. 6]) or

pores (poppy [fig. 7], _Campanula_, &c.); the seeds are in these cases

small and numerous, and are jerked through the pores when the

capsules, which are generally borne on long, dry stems or stalks, are

shaken by the wind. (4) In other cases members of the animal world aid

in seed-dispersal. Fruits often bear stiff hairs or small hooks, which

cling to the coat of an animal or the feathers of a bird; such are

fruits of cleavers (_Galium Aparine_), a common hedge-row plant,

_Ranunculus arvensis_ (fig. 20), carrot, _Geum_, &c.; or the fruit or

seed has an often bright-coloured, fleshy covering, which is sought by

birds as food, as in stone-fruits such as plum, cherry (fig. 5), &c.,

where the seed is protected from injury in the mouth or stomach of the

animal by the hard endocarp; or the hips of the rose (fig. 3), where

the succulent scarlet "fruit" (the swollen receptacle) envelops a

number of small dry true fruits (achenes), which cling by means of

stiff hairs to the beak of the bird.

[Illustration:

FIG. 22.--Vertical section of a grain of wheat, showing embryo below

at the base of the endosperm e; s, scutellum separating embryo from

endosperm; f.l, foliage leaf; p.s, sheath of plumule; p.r, primary

root; s.p.r, sheath of primary root.

FIG. 23.--Fruit of Comfrey (_Symphytum_) surrounded by persistent

calyx, c. The style s appears to arise from the base of the carpels,

enlarged.

FIG. 24.--Ovary of _Foeniculum officinale_ with pendulous ovules, in

longitudinal section. (After Berg and Schmidt, magnified.)

From Strasburger's _Lehrbuch der Botanik_, by permission of Gustav

Fischer.

FIG. 25.--Fruit of _Carum Carui_. A, Ovary of the flower; B, ripe

fruit. The two carpels have separated so as to form two mericarps

(m). Part of the septum constitutes the carpophore (a). p, Top of

flower-stalk; d, disk on top of ovary; n, stigma.

From Vines' _Students' Text-Book of Botany_, by permission of Swan

Sonnenschein & Co.]

Forms of fruit.

Simple fruits have either a _dry_ or _succulent_ pericarp. The

_achene_ is a dry, one-seeded, indehiscent fruit, the pericarp of

which is closely applied to the seed, but separable from it. It is

solitary, forming a single fruit, as in the dock (fig. 19) and in the

cashew, where it is supported on a fleshy peduncle; or _aggregate_, as

in _Ranunculus_ (fig. 20), where several achenes are placed on a

common elevated receptacle. In the strawberry the achenes (fig. 2) are

aggregated on a convex succulent receptacle. In the rose they are

supported on a concave receptacle (fig. 3), and in the fig the

succulent receptacle completely encloses the achenes (fig. 4). In

_Dorstenia_ the achenes are situated on a flat or slightly concave

receptacle. Hence what in common language are called the seeds of the

strawberry, rose and fig, are in reality ripe carpels. The styles

occasionally remain attached to the achenes in the form of feathery

appendages, as in _Clematis_. In Compositae, the fruit is an inferior

achene (_cypsela_), to which the pappus (modified calyx) remains

adherent. Such is also the nature of the fruit in Dipsacaceae (e.g.

scabious). When the pericarp is thin, and appears like a bladder

surrounding the seed, the achene is termed a _utricle_, as in

Amarantaceae. When the pericarp is extended in the form of a winged

appendage, a _samara_ or _samaroid achene_ is produced, as in the ash

(fig. 1) and common sycamore (fig. 21). In these cases there are

usually two achenes united, one of which, however, as in _Fraxinus_

(fig. 1), may be abortive. The wing surrounds the fruit longitudinally

in the elm. When the pericarp becomes so incorporated with the seed as

to be inseparable from it, as in grains of wheat (fig. 22), maize,

oats and other grasses, then the name _caryopsis_ is given. The

one-seeded portions (mericarps) of schizocarps often take the form of

achenes, e.g. the mericarps of the mallows or of umbellifers (figs.

24, 25). In Labiatae and Boraginaceae (e.g. comfrey, fig. 23), where

the bicarpellary ovary becomes our one-seeded portions in the fruit,

the partial fruits are of the nature of achenes or nutlets according

to the texture (leathery or hard) of the pericarp.

[Illustration: From Strasburger's _Lehrbuch der Botanik_, by

permission of Gustav Fischer.

FIG. 26.--Cupule of _Quercus Aegilops_. cp, cupule; gl, fruit.

(After Duchartre.)]

The _nut_ or _glans_ is a dry one-celled indehiscent fruit with a

hardened pericarp, often surrounded by bracts at the base, and, when

mature, containing only one seed. In the young state the ovary often

contains two or more ovules, but only one comes to maturity. It is

illustrated by the fruits of the hazel and chestnut, which are covered

by leafy bracts, in the form of a _husk_, and by the acorn, in which

the bracts and receptacle form a _cupula_ or _cup_ (fig. 26). The

parts of the pericarp of the nut are united so as to appear one. In

common language the term nut is very vaguely applied both to fruit and

seeds.

The _drupe_ is a succulent usually one-seeded indehiscent fruit, with

a pericarp easily distinguishable into epicarp, mesocarp and endocarp.

This term is applied to such fruits as the cherry (fig. 5), peach,

plum, apricot or mango. The endocarp is usually hard, forming the

stone (putamen) of the fruit, which encloses the kernel or seed. The

mesocarp is generally pulpy and succulent, so as to be truly a

sarcocarp, as in the peach, but it is sometimes of a tough texture, as

in the almond, and at other times is more or less fibrous, as in the

coco-nut. In the almond there are often two ovules formed, only one of

which comes to perfection. In the raspberry and bramble several small

drupes or _drupels_ are aggregated so as to constitute an _etaerio_.

The _follicle_ is a dry unilocular many-seeded fruit, formed from one

carpel and dehiscing by the ventral suture. It is rare to meet with a

solitary follicle forming the fruit. There are usually several

aggregated together, either in a whorl on a shortened receptacle, as

in hellebore, aconite, larkspur, columbine (figs. 27, 28) or the order

Crassulaceae, or in a spiral manner on an elongated receptacle, as in

_Magnolia_ and _Banksia_. Occasionally, follicles dehisce by the

dorsal suture, as in _Magnolia grandiflora_ and _Banksia_.

[Illustration:

FIG. 27.--Fruit of Columbine (_Aquilegia_), formed of five

follicles.

FIG. 28.--Single follicle, showing dehiscence by the ventral suture.

FIG. 29.--Transverse section of berry of Gooseberry, showing the

seeds attached to the parietal placentas and immersed in pulp, which

is formed partly from the endocarp, partly from the seed-coat.

FIG. 30.--Section of the fruit of the Apple (_Pyrus Malus_), or

pome, consisting of a fleshy covering formed by the floral

receptacle and the true fruit or core with five cavities with

seeds.]

The _legume_ or _pod_ is a dry monocarpellary unilocular many-seeded

fruit, formed from one carpel, dehiscing both by the ventral and the

dorsal suture. It characterizes leguminous plants, as the bean and pea

(fig. 8). In the bladder-senna it forms an inflated legume. In some

Leguminosae, as _Arachis_, _Cathartocarpus Fistula_ and the tamarind,

the fruit must be considered a legume, although it does not dehisce.

The first of these plants produces its fruit underground, and is

called earth-nut; the second has a partitioned legume and is

schizocarpic; and both the second and third have pulpy matter

surrounding the seeds. Some legumes are schizocarpic by the formation

of constrictions externally. Such a form is the _lomentum_ or

_lomentaceous legume_ of _Hedysarum_ (fig. 17), _Coronilla_,

_Ornithopus_, _Entada_ and of some Acacias. In _Medicago_ the legume

~~ is twisted like a snail, and in _Caesalpinia coriaria_, or

Divi-divi, it is vermiform or curved like a worm. Sometimes the number

of seeds is reduced, as in _Erythrina monosperma_ and _Geoffroya

superba_, which are one-seeded, and in _Pterocarpus_ and _Dalbergia_,

which are two-seeded.

[Illustration: FIG. 31.--Transverse section of the fruit of the Melon

(_Cucumis Melo_), showing the placentas with the seeds attached to

them. The three carpels forming the pepo are separated by partitions.

From the centre processes pass outwards, ending in the curved

placenta.

The _berry_ (_bacca_) is a term applied generally to all fruits with

seeds immersed in pulp, and includes fruits of very various origin. In

_Actaea_ (baneberry) or _Berberis_ (barberry) it is derived from a

single free carpel; generally, however, it is the product of a

syncarpous ovary, which is superior, as in grape or potato, or

inferior, as in gooseberry (fig. 29) or currant. In the pomegranate

there is a peculiar baccate many-celled inferior fruit, having a tough

rind, enclosing two rows of carpels placed one above the other. The

seeds are immersed in pulp, and are attached irregularly to the wall,

base and centre of the loculi. In the baobab there is a multilocular

syncarpous fruit, in which the seeds are immersed in pulp.

The _pepo_, another indehiscent syncarpous fruit, is illustrated by

the fruit of the gourd, melon (fig. 31) and other Cucurbitaceae. It is

formed of three carpels, surmounted by the calyx; the rind is thick

and fleshy, and there are three or more seed-bearing parietal

placentas, either surrounding a central cavity or prolonged inwards

into it. The fruit of the papaw resembles the pepo, but the calyx is

not superior.

The _hesperidium_ is the name given to such indehiscent fleshy

syncarpous fruits as the orange, lemon and shaddock, in which the

epicarp and mesocarp form a separable rind, and the endocarp sends

prolongations inwards, forming triangular divisions, to the inner

angle of which the seeds are attached, pulpy cells being developed

around them from the wall. Both pepo and hesperidium may be considered

as modifications of the berry.

The _pome_ (fig. 30), seen in the apple, pear, quince, medlar and

hawthorn, is a fleshy indehiscent syncarpous fruit, in the formation

of which the receptacle takes part. The outer succulent part is the

swollen receptacle, the horny core being the true fruit developed from

the usually five carpels and enclosing the seeds. In the medlar the

core (or true pericarp) is of a stony hardness, while the outer

succulent covering is open at the summit. The pome somewhat resembles

the fruit of the rose (fig. 3), where the succulent receptacle

surrounds a number of separate achenes.

The name _capsule_ is applied generally to all dry syncarpous fruits,

which dehisce by valves. It may thus be unilocular or multilocular,

one- or many-seeded. The true valvular capsule is observed in

_Colchicum_ (fig. 9), lily and iris (fig. 11). The _porose capsule_ is

seen in the poppy (fig. 7), _Antirrhinum_ and _Campanula_. In

_Campanula_ the pores occur at the base of the capsule, which becomes

inverted when ripe. When the capsule opens by a lid, or by

circumscissile dehiscence, it is called a _pyxidium_, as in pimpernel

(_Anagallis arvensis_) (fig. 16), henbane and monkey-pot (_Lecythis_).

The capsule assumes a screw-like form in _Helicteres_, and a star-like

form in star-anise (_Illicium anisatum_). In certain instances the

cells of the capsule separate from each other, and open with

elasticity to scatter the seeds. This kind of capsule is met with in

the sandbox tree (_Hura crepitans_) and other Euphorbiaceae, where the

cocci, containing each a single seed, burst asunder with force; and in

Geraniaceae, where the cocci, each containing, when mature, usually

one seed, separate from the carpophore, become curved upwards by their

adherent styles, and open by the ventral suture (fig. 18).

The _siliqua_ is a dry syncarpous bilocular many-seeded fruit, formed

from two carpels, with a false septum, dehiscing by two valves from

below upwards, the valves separating from the placentas and leaving

them united by the septum (fig. 32). The seeds are attached on both

sides of the septum, either in one row or in two. When the fruit is

long and narrow it is a _siliqua_ (fig. 14); when broad and short,

_silicula_ (fig. 33). It occurs in cruciferous plants, as wallflower,

cabbage and cress. In _Glaucium_ and _Eschscholtzia_ (Papaveraceae)

the dissepiment is of a spongy nature. It may become transversely

constricted (_lomentaceous_), as in radish (_Raphanus_) and sea-kale,

and it may be reduced, as in woad (_Isatis_), to a one-seeded

condition.

It sometimes happens that the ovaries of two flowers unite so as to

form a double fruit (_syncarp_). This may be seen in many species of

honeysuckle. But the 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_ or _confluent_. 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 pine-apple (fig. 34),

the bread-fruit and jack-fruit. Similarly the fruit of the mulberry

represents a catkin-like inflorescence.

The _syconus_ is an anthocarpous fruit, in which the receptacle

completely encloses numerous flowers and becomes succulent. The fig

(fig. 4) is of this nature, and what are called its seeds are the

achenes of the numerous flowers scattered over the succulent hollowed

receptacle. In _Dorstenia_ the axis is less deeply hollowed, and of a

harder texture, the fruit exhibiting often very anomalous forms.

The _strobilus_, or _cone_, is a seed-bearing spike, more or less

elongated, covered with scales, each of which may be regarded as

representing a separate flower, and has often two seeds at its base;

the seeds are naked, no ovary being present. This fruit is seen in the

cones of firs, spruces, larches and cedars, which have received the

name of Coniferae, or cone-bearers, on this account. Cone-like fruit

is also seen in most Cycadaceae. The scales of the strobilus are

sometimes thick and closely united, so as to form a more or less

angular and rounded mass, as in the cypress; while in the 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_. 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.

[Illustration:

FIG. 32.--Honesty (_Lunaria biennis_), showing the septum after the

carpels have fallen away.

From Strasburger's _Lehrbuch der Botanik_, by permission of Gustav

Fischer.

FIG. 33.--Silicula or pouch of shepherd's purse (_Capsella_),

opening by two folded valves, which separate from above downwards.

The partition is narrow, hence the silicula is angustiseptal.

From Strasburger's _Lehrbuch der Botanik_, by permission of Gustav

Fischer.

FIG. 34.--Fruit of the pine-apple (_Ananassa sativa_), developed

from a spike of numerous flowers with bracts, united so as to form a

collective or anthocarpous fruit. The crown of the pine-apple, c,

consists of a series of empty bracts prolonged beyond the fruit.]

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 sometimes changed into leaves, with

lobes at their margins. Leaves are sometimes produced from the upper

part of the fruit. In the genus _Citrus_, to which the orange and

lemon belong, it is very common to meet with a separation of the

carpels, so as to produce what are 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 the appearance of small and imperfect

oranges enclosed within the original one; the navel orange 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._

A. True fruits--developed from the ovary alone.

1. Pericarp not fleshy or fibrous.

i. Indehiscent--not opening to allow the escape of the

seeds--generally one-seeded. Achene; caryopsis; cypsela;

nut; schizocarp.

ii. Dehiscent--the pericarp splits to allow the escape of the

seeds--generally many-seeded. Follicle; legume; siliqua;

capsule.

2. Pericarp generally differentiated into distinct layers, one

of which is succulent or fibrous. Drupe; berry.

B. Pseudocarps--the development extends beyond the ovary. Pome;

syconus; sorosis.

_The Seed._--The _seed_ is formed from the ovule as the result of

fertilization. It is contained in a seed-vessel formed from the ovary

in the plants called _angiospermous_; while in _gymnospermous_

plants, such as Coniferae and Cycadaceae, 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 development; this

occurs in mignonette, where the capsule opens at the apex, and in

_Cuphea_, where the placenta bursts through the ovary and floral

envelopes, and appears as an erect process bearing the young seeds.

After fertilization the ovule is greatly changed, in connexion with

the formation of the embryo. In the embryo-sac of most Angiosperms

(q.v.) there is a development of cellular tissue, the endosperm, more

or less filling the embryo-sac. In Gymnosperms (q.v.) the endosperm is

formed preparatory to fertilization. The fertilized egg enlarges and

becomes multicellular, forming the embryo. The embryo-sac enlarges

greatly, displacing gradually the surrounding nucellus, which

eventually forms merely a thin layer around the sac, or completely

disappears. The remainder of the nucellus and the integuments of the

ovules form the seed-coats. In some cases (fig. 35) a delicate inner

coat or _tegmen_ can be distinguished from a tougher outer coat or

_testa_; often, however, the layers are not thus separable. The

consistency of the seed-coat, its thickness, the character of its

surface, &c., vary widely, the variations being often closely

associated with the environment or with the means of seed-dispersal.

An account of the development of the seed from the ovule will be found

in the article ANGIOSPERMS. When the pericarp is dehiscent the

seed-covering is of a strong and often rough character; but when the

pericarp is indehiscent and encloses the seed for a long period, the

outer seed-coat is thin and soft. The cells of the testa are often

coloured, and have projections and appendages of various kinds. Thus

in _Abrus precatorius_ and _Adenanthera pavonina_ it is of a bright

red colour; in French beans it is beautifully mottled; in the almond

it is veined; in the tulip and primrose it is rough; in the snapdragon

it is marked with depressions; in cotton and _Asclepias_ (fig. 36) it

has hairs attached to it; and in mahogany, _Bignonia_, and the pines

and firs it is expanded in the form of wing-like appendages (fig. 37).

In _Collomia_, _Acanthodium_, _Cobaea scandens_ and other seeds, it

contains spiral cells, from which, when moistened with water, the

fibres uncoil in a beautiful manner; and in flax (_Linum_) and others

the cells are converted into mucilage. These structural peculiarities

of the testa in different plants have relation to the scattering of

the seed and its germination upon a suitable nidus. But in some plants

the pericarps assume structures which subserve the same purpose; this

especially occurs in small pericarps enclosing single seeds, as

achenes, caryopsides, &c. Thus in Compositae and valerian, the pappose

limb of the calyx forms a parachute to the pericarp; in Labiatae and

some Compositae spiral cells are formed in the epicarp; and the

epicarp is prolonged as a wing in _Fraxinus_ (fig. 1) and _Acer_ (fig.

21).

[Illustration:

FIG. 35.--Seed of Pea (_Pisum_) with one cotyledon removed. c,

Remaining cotyledon; ch, chalaza-point at which the nourishing

vessels enter; e, tegmen or inner coat; f, funicle or stalk; g,

plumule of embryo; m, micropyle; pl, placenta; r, radicle of embryo;

t, tigellum or stalk between root and plumule; te, testa.

FIG. 36.--Seed of _Asclepias_, with a cluster of hairs arising from

the edges of the micropyle.]

Sometimes there is an additional covering to the seed, formed after

fertilization, to which the name _arillus_ has been given (fig. 38).

This is seen in the passion-flower, where the covering arises from the

placenta or extremity of the funicle at the base of the ovule and

passes upwards towards the apex, leaving the micropyle uncovered. In

the nutmeg and spindle tree this additional coat is formed from above

downwards, constituting in the former case a laciniated scarlet

covering called _mace_. In such instances it has been called an

_arillode_ (fig. 39). This arillode, after growing downwards, may be

reflected upwards so as to cover the micropyle. The fleshy scarlet

covering formed around the naked seed in the yew is by some considered

of the nature of an aril. On the testa, at various points, there are

produced at times other cellular bodies, to which the name of

_strophioles_, or _caruncles_, has been given, the seeds being

strophiolate or carunculate. These tumours may occur near the base of

the seed, as in _Polygala_, or at the apex, as in Castor-oil plant

(_Ricinus_); or they may occur in the course of the raphe, as in

blood-root (_Sanguinaria_) and _Asarabacca_. The funicles of the

ovules frequently attain a great length in the seed, and in some

magnolias, when the fruit dehisces, they appear as long scarlet cords

suspending the seeds outside. The hilum or umbilicus of the seed is

usually well marked, as a scar of varying size; in the calabar bean

and in some species of Mucuna and Dolichos it extends along a large

portion of the edge of the seed; it frequently exhibits marked

colours, being black in the bean, white in many species of Phaseolus,

&c. The micropyle (fig. 35, m) of the seed may be recognizable by the

naked eye, as in the pea and bean tribe, _Iris_, &c., or it may be

very minute or microscopic. It indicates the true apex of the seed,

and is important as marking the point to which the root of the embryo

is directed. At the micropyle in the bean is observed a small process

of integument, which, when the young plant sprouts, is pushed up like

a lid; it is called the _embryotega_. The chalaza (fig. 38, ch) is

often of a different colour from the rest of the seed. In the orange

(fig. 40) it is of a reddish-brown colour, and is easily recognized at

one end of the seed when the integuments are carefully removed. In

anatropal seeds the raphe forms a distinct ridge along one side of the

seed (fig. 41).

The position of the seed as regards the pericarp resembles that of the

ovule in the ovary, and the same terms are applied--erect, ascending,

pendulous, suspended, curved, &c. These terms have no reference to the

mode in which the fruit is attached to the axis. Thus the seed may be

erect while the fruit itself is pendent, in the ordinary meaning of

that term. The part of the seed next the axis or the ventral suture is

its face, the opposite side being the back. Seeds exhibit great

varieties of form. They may be flattened laterally (_compressed_), or

from above downwards (_depressed_). They may be round, oval,

triangular, polygonal, rolled up like a snail, as in _Physostemon_, or

coiled up like a snake, as in _Ophiocaryon paradoxum_.

[Illustration:

FIG. 37.--Seed of Pine (_Pinus_), with a membranous appendage w to

the testa, called a wing.

FIG. 38.--Young anatropal seed of the white Water-lily (_Nymphaea

alba_), cut vertically. It is attached to the placenta by the

funicle f, cellular prolongations from which form an aril a a. The

vessels of the cord are prolonged to the base of the nucellus n by

means of the raphe r. The base of the nucellus is indicated by the

chalaza ch, while the apex is at the micropyle m. The covering of

the seed is marked i. n is the nucellus or perisperm, enclosing the

embryo-sac es, in which the endosperm is formed. The embryo e, with

its suspensor, is contained in the sac, the radicle pointing to the

micropyle m.

FIG. 39.--Arillode a, or false aril, of the Spindle-tree

(_Euonymus_), arising from the micropyle f.

FIG. 40.--Anatropal seed of the Orange (_Citrus Aurantium_) opened

to show the chalaza c, which forms a brown spot at one end.

FIG. 41.--Entire anatropal seed of the Orange (_Citrus Aurantium_),

with its rugose or wrinkled testa, and the raphe r ramifying in the

thickness of the testa on one side.]

The endosperm formed in the embryo-sac of angiosperms after

fertilization, and found previous to it in gymnosperms, consists of

cells containing nitrogenous and starchy or fatty matter, destined for

the nutriment of the embryo. It occupies the whole cavity of the

embryo-sac, or is formed only at certain portions of it, at the apex,

as in _Rhinanthus_, at the base, as in _Vaccinium_, or in the middle,

as in _Veronica_. As the endosperm increases in size along with the

embryo-sac and the embryo, the substance of the original nucellus of

the ovule is gradually absorbed. Sometimes, however, as in Musaceae,

Cannaceae, Zingiberaceae, no endosperm is formed; the cells of the

original nucellus, becoming filled with food-materials for the embryo,

are not absorbed, but remain surrounding the embryo-sac with the

embryo, and constitute the _perisperm_. Again, in other plants, as

Nymphaeaceae (fig. 38) and Piperaceae, both endosperm and perisperm

are present. It was from observations on cases such as these that old

authors, imagining a resemblance betwixt the plant-ovule and the

animal ovum, applied the name _albumen_ to the outer nutrient mass or

perisperm, and designated the endosperm as _vitellus_. The term

albumen is very generally used as including all the nutrient matter

stored up in the seed, but it would be advisable to discard the name

as implying a definite chemical substance. There is a large class of

plants in which although at first after fertilization a mass of

endosperm is formed, yet, as the embryo increases in size, the

nutrient matter from the endospermic cells passes out from them, and

is absorbed by the cells of the embryo plant. In the mature seed, in

such cases, there is no separate mass of tissue containing nutrient

food-material apart from the embryo itself. Such a seed is said to be

_exalbuminous_, as in Compositae, Cruciferae and most Leguminosae

(e.g. pea, fig. 35). When either endosperm or perisperm or both are

present the seed is said to be _albuminous_.

[Illustration: FIG. 42.--The dicotyledonous embryo of the Pea laid

open. c, c, The two fleshy cotyledons, or seed-lobes, which remain

under ground when the plant sprouts; r, the radicular extremity of the

axis whence the root arises; t, the axis (hypocotyl) bearing the young

stalk and leaves g (plumule), which lie in a depression of the

cotyledons f.]

The albumen varies much in its nature and consistence, and furnishes

important characters. It may be farinaceous or mealy, consisting

chiefly of cells filled with starch, as in cereal grains, where it is

abundant; fleshy or cartilaginous, consisting of thicker cells which

are still soft, as in the coco-nut, and which sometimes contain oil,

as in the oily albumen of _Croton_, _Ricinus_ and poppy; horny, when

the cell-walls are slightly thickened and capable of distension, as in

date and coffee; the cell-walls sometimes become greatly thickened,

filling up the testa as a hard mass, as in vegetable ivory

(_Phytelephas_). The albumen may be uniform throughout, or it may

present a mottled appearance, as in the nutmeg, the seeds of Anonaceae

and some Palms, where it is called _ruminated_. This mottled

appearance is due to a protrusion of a dark lamella of the integument

between folded protuberances of albumen. A cavity is sometimes left in

the centre which is usually filled with fluid, as in the coco-nut. The

relative size of the embryo and of the endosperm varies much. In

Monocotyledons the embryo is usually small, and the endosperm large,

and the same is true in the case of coffee and many other plants

amongst Dicotyledons. The opposite is the case in other plants, as in

the Labiatae, Plumbaginaceae, &c.

The embryo consists of an axis bearing the _cotyledons_ (fig. 42, c),

or the first leaves of the plant. To that part of this axis

immediately beneath the cotyledons the terms _hypocotyl_, _caulicle_

or _tigellum_ (t) have been applied, and continuous backwards with it

is the young root or _radicle_ (r), the descending axis, their point

of union being the collar or neck. The terminal growing bud of the

axis is called the _plumule_ or _gemmule_ (g), and represents the

ascending axis. The radicular extremity points towards the micropyle,

while the cotyledonary extremity is pointed towards the base of the

ovule or the chalaza. Hence, by ascertaining the position of the

micropyle and chalaza, the two extremities of the embryo can in

general be discovered. It is in many cases difficult to recognize the

parts in an embryo; thus in _Cuscuta_, the embryo appears as an

elongated axis without divisions; and in _Caryocar_ the mass of the

embryo is made up by the radicular extremity and hypocotyl, in a

groove of which the cotyledonary extremity lies embedded (fig. 52). In

some monocotyledonous embryos, as in Orchidaceae, the embryo is a

cellular mass showing no parts. In parasitic plants also which form no

chlorophyll, as _Orobanche_, _Monotropa_, &c., the embryo remains

without differentiation, consisting merely of a mass of cells until

the ripening of the seed. When the embryo is surrounded by the

endosperm on all sides except its radicular extremity it is internal

(see figs. 19, 20); when lying outside the endosperm, and only coming

into contact with it at certain points, it is external, as in grasses

(e.g. wheat, fig. 22). When the embryo follows the direction of the

axis of the seed, it is axile or axial (fig. 43); when it is not in

the direction of the axis, it becomes abaxile or abaxial. In

campylotropal seeds the embryo is curved, and in place of being

embedded in endosperm, is frequently external to it, following the

concavity of the seed (fig. 44), and becoming peripherical, with the

chalaza situated in the curvature of the embryo, as in

Caryophyllaceae.

It has been already stated that the radicle of the embryo is directed

to the micropyle, and the cotyledons to the chalaza. In some cases, by

the growth of the integuments, the former is turned round so as not to

correspond with the apex of the nucellus, and then the embryo has the

radicle directed to one side, and is called excentric, as is seen in

Primulaceae, Plantaginaceae and many palms, especially the date. The

position of the embryo in different kinds of seeds varies. In an

orthotropal seed the embryo is inverted or _antitropal_, the radicle

pointing to the apex of the seed, or to the part opposite the hilum.

Again, in an anatropal seed the embryo is erect or _homotropal_ (fig.

43), the radicle being directed to the base of the seed. In curved or

campylotropal seeds the embryo is folded so that its radicular and

cotyledonary extremities are approximated, and it becomes

_amphitropal_ (fig. 44). In this instance the seed may be

exalbuminous, and the embryo may be folded on itself; or albuminous,

the embryo surrounding more or less completely the endosperm and being

peripherical. According to the mode in which the seed is attached to

the pericarp, the radicle may be directed upwards or downwards, or

laterally, as regards the ovary. In an orthotropal seed attached to

the base of the pericarp it is superior, as also in a suspended

anatropal seed. In other anatropal seeds the radicle is inferior. When

the seed is horizontal as regards the pericarp, the radicle is either

centrifugal, when it points to the outer wall of the ovary; or

centripetal, when it points to the axis or inner wall of the ovary.

These characters are of value for purposes of classification, as they

are often constant in large groups of genera.

Plants in which there are two cotyledons produced in the embryo are

_dicotyledonous_. The two cotyledons thus formed are opposite to each

other (figs. 42 and 45), but are not always of the same size. Thus, in

Abronia and other members of the order Nyctaginaceae, one of them is

smaller than the other (often very small), and in _Carapa guianensis_

there appears to be only one, in consequence of the intimate union

which takes place between the two. The union between the cotyledonary

leaves may continue after the young plant begins to germinate. Such

embryos have been called _pseudomonocotyledonous_. The texture of the

cotyledons varies. They may be thick, as in the pea (fig. 42),

exhibiting no traces of venation, with their flat internal surfaces in

contact, and their backs more or less convex; or they may be in the

form of thin and delicate laminae, flattened on both sides, and having

distinct venation, as in _Ricinus_, _Jatropha_, _Euonymus_, &c. The

cotyledons usually form the greater part of the mature embryo, and

this is remarkably well seen in such exalbuminous seeds as the bean

and pea.

[Illustration:

FIG. 43.--Seed of Pansy (_Viola tricolor_) cut vertically. The

embryo pl is axial, in the midst of fleshy endosperm al. The seed is

anatropal, and the embryo is homotropal; the cotyledons co point to

the base of the nucellus or chalaza ch, while the radicle, or the

other extremity of the embryo, points to the micropyle, close to the

hilum h. The hilum or base of the seed, and the chalaza or base of

the nucellus are united by means of the raphe r.

FIG. 44.--Seed of the Red Campion (_Lychnis_), cut vertically,

showing the peripheral embryo, with its two cotyledons and its

radicle. The embryo is curved round the albumen, so that its

cotyledons and radicle both come near the hilum (_amphitropal_).

FIG. 45.--Mature dicotyledonous embryo of the Almond, with one of

the cotyledons removed. r, Radicle; t, young stem or caulicle; c,

one of the cotyledons left; i, line of insertion of the cotyledon

which has been removed; g, plumule.

FIG. 46.--Exalbuminous seed of Wallflower (Cheiranthus) cut

vertically. The radicle r is folded on the edges of the cotyledons c

which are accumbent.

FIG. 47.--Transverse section of the seed of the Wallflower

(_Cheiranthus_), showing the radicle r folded on the edges of the

accumbent cotyledons c.

FIG. 48.--Transverse section of the seed of the Dame's Violet

(_Hesperis_). The radicle r is folded on the back of the cotyledons

c, which are said to be incumbent.]

Cotyledons are usually entire and sessile. But they occasionally

become lobed, as in the walnut and the lime; or petiolate, as in

_Geranium molle_; or auriculate, as in the ash. Like leaves in the

bud, cotyledons may be either applied directly to each other, or may

be folded in various ways. In geranium the cotyledons are twisted and

doubled; in convolvulus they are corrugated; and in the potato and in

_Bunias_, they are spiral,--the same terms being applied as to the

foliage leaves. The radicle and cotyledons are either straight or

variously curved. Thus, in some cruciferous plants, as the wallflower,

the cotyledons are applied by their faces, and the radicle (figs. 46,

47) is folded on their edges, so as to be lateral; the cotyledons are

here _accumbent_. In others, as _Hesperis_, the cotyledons (fig. 48)

are applied to each other by their faces, and the radicle, r, is

folded on their back, so as to be dorsal, and the cotyledons are

_incumbent_. Again, the cotyledons are _conduplicate_ when the radicle

is dorsal, and enclosed between their folds. In other divisions the

radicle is folded in a spiral manner, and the cotyledons follow the

same course.

In many gymnosperms more than two cotyledons are present, and they are

arranged in a whorl. This occurs in Coniferae, especially in the pine,

fir (fig. 49), spruce and larch, in which six, nine, twelve and even

fifteen have been observed. They are linear, and resemble in their

form and mode of development the clustered or fasciculated leaves of

the larch. Plants having numerous cotyledons are termed

_polycotyledonous_. In species of _Streptocarpus_ the cotyledons are

permanent, and act the part of leaves. One of them is frequently

largely developed, while the other is small or abortive.

[Illustration:

FIG. 49.--Polycotylodonous embryo of the Pine (_Pinus_) beginning to

sprout. t, Hypocotyl; r, radicle. The cotyledons c are numerous.

Within the cotyledons the primordial leaves are seen, constituting

the plumule or first bud of the plant.

FIG. 50.--Embryo of a species of Arrow-grass (_Triglochin_), showing

a uniform conical mass, with a slit s near the lower part. The

cotyledon c envelops the young bud, which protrudes at the slit

during germination. The radicle is developed from the lower part of

the axis r.

FIG. 51.--Grain of wheat (_Triticum_) germinating, showing (b) the

cotyledon and (c) the rootlets surrounded by their sheaths

(_coleorrhizae_).

FIG. 52.--Embryo of _Caryocar_. t, Thick hypocotyl, forming nearly

the whole mass, becoming narrowed and curved at its extremity, and

applied to the groove s. In the figure this narrowed portion is

slightly separated from the groove; c, two rudimentary cotyledons.]

In those plants in which there is only a single cotyledon in the

embryo, hence called _monocotyledonous_, the embryo usually has a

cylindrical form more or less rounded at the extremities, or elongated

and fusiform, often oblique. The axis is usually very short compared

with the cotyledon, which in general encloses the plumule by its lower

portion, and exhibits on one side a small slit which indicates the

union of the edges of the vaginal or sheathing portion of the leaf

(fig. 50). In grasses, by the enlargement of the embryo in a

particular direction, the endosperm is pushed on one side, and thus

the embryo comes to lie outside at the base of the endosperm (figs.

22, 51). The lamina of the cotyledon is not developed. Upon the side

of the embryo next the endosperm and enveloping it is a large

shield-shaped body, termed the _scutellum_. This is an outgrowth from

the base of the cotyledon, enveloping more or less the cotyledon and

plumule, in some cases, as in maize, completely investing it; in other

cases, as in rice, merely sending small prolongations over its

anterior face at the apex. By others this scutellum is considered as

the true cotyledon, and the sheathing structure covering the plumule

is regarded as a ligule or axillary stipule (see GRASSES). In many

aquatic monocotyledons (e.g. _Potamogeton_, _Ruppia_ and others) there

is a much-developed hypocotyl, which forms the greater part of the

embryo and acts as a store of nutriment in germination; these are

known as _macropodous_ embryos. A similar case is that of _Caryocar_

among Dicotyledons, where the swollen hypocotyl occupies most of the

embryo (fig. 52). In some grasses, as oats and rice, a projection of

cellular tissue is seen upon the side of the embryo opposite to the

scutellum, that is, on the anterior side. This has been termed the

_epiblast_. It is very large in rice. This by some was considered the

rudimentary second cotyledon; but is now generally regarded as an

outgrowth of the sheath of the true cotyledon. (A. B. R.)

FRUIT AND FLOWER FARMING. The different sorts of fruits and flowers are

dealt with in articles under their own headings, to which reference may

be made; and these give the substantial facts as to their cultivation.