2d. Raceme, (Fig. 88, a,) consists of numerous flowers, each on its own stalk, and all arranged on one common peduncle, as in the locust and currant.

3d. Panicle, (Fig. 88, b,) bears the flowers in a kind of loose, subdivided bunch or cluster, without any regular order; as in the oat, and some other grasses. A panicle contracted into a compact, somewhat ovate form, as in the lilac, is called a thyrse, as a bunch of grapes.

4th. Spike, (Fig. 89, a,) this is an assemblage of flowers arising from the sides of a common stem; the flowers are sessile or with

very short peduncles; as the grasses and mullein. A spike is generally erect. The lowest flowers usually blossom and fade before the upper ones expand. When the flowers in a spike are crowded very close, an ear is formed, as in Indian

corn.

5th. Umbel, (Fig. 89, b,) consists of several flower-stalks, of nearly equal length, spreading out from a common centre, like the rays of an umbrella, bearing flowers on their summits; as fennel and carrot.

Fig. 89.

Raceme-Panicle-Spike-Umbel.

6th. Cyme, (Fig. 90, c,) resembles an umbel in having its common stalks all spring from one centre, but differs in having those stalks irregularly subdivided; as the snowball and elder.

Fig. 90.

a

b

7th. Corymb, (Fig. 90, a,) or false umbel; when the peduncles rise from different heights above the main stem, but the lower ones being longer, they form nearly a level or convex top; as the yarrow.

8th. Fascicle, (Fig. 90, b,) flowers on little stalks variously inserted and subdivided, collected into a close bundle, nearly level at the top; as the sweet-william; it resembles a corymb, but the flowers are more densely clustered.

9th. Head, (Fig. 90, c,) or tuft, has sessile flowers heaped together in a globular form; as in the clover, and button bush, (cephalanthus.)

10th. Ament or catkin, is an assemblage of flowers, composed of scales and stamens, or pistils arranged along a common thread-like receptacle, as in the chestnut and willow; this, though described under the divisions of the calyx, is only a mode of inflorescence. The scales of the ament are properly the calyxes; the whole aggregate, including scales, stamens or pistils, and filiform receptacle, constitutes the Fig. 91. ament. At Fig. 91, is the representation of the ament of the poplar, containing pistillate flowers; this is oblong, loosely imbricated, and cylindrical; the calyx is a flat scale, with deep-fringed partings. At b, is a representation of the fertile or pistillate flower; the calyx or bract is a little below the corolla, which is cup-shaped, of one petal, and crowned with an egg-shaped, pointed germ; the germ is superior, and bears four (sometimes eight) stigmas.

The staminate ament resembles the pistillate, except that its corolla encloses eight stamens, but no pistil. The poplar is in the class Diccia, because the pistillate and staminate flowers are on

Cyme-Corymb-Fascicle-Head-Ament.

different trees; and of the order Octandria, because its barren flowers have eight stamens.

18

B

b

A

11th, Spadix, is an assemblage of flowers growing upon a a common receptacle, and surrounded by a spatha or sheath. At Fig. 92, A, a, is a representation of the blossom of the wild turnip, (arum ;) a

represents the spatha, which is erect, sheathing, oblong, convolute at the base, b; and it is compressed above and below the middle; c, represents the spadix, which, from its club-shaped appearance, is called clavi-form, (from clava, a club.)

At B, is the spadix divested of the spatha; a, is the claviform summit; b, a ring of filaments without anthers; c, a ring of sessile anthers; d, a dense ring of pistillate flowers with sessile stigmas; each germ produces a one-celled, globular berry. This plant is of the class Monœcia, because its staminate and pistillate flowers are separate, but yet grow on the same plant; it is in the order Polyandria, because its stamens are numerous.

Receptacle.

The receptacle is the extremity of the peduncle, it is also called the clinanthe,* from kline, bed, and anthos, flower; at first it supports the flower, and afterward the fruit. As this is its only use, it may properly be considered in connexion with the organs of fructification. In simple flowers, as the tulip, the receptacle is scarcely to be distinguished from the peduncle, but in compound flowers it is expanded, and furnishes a support for the flowers and fruit. Receptacles are of various kinds; as,

1st. Proper, which supports but one flower, as in the violet and lily.

2d. Common, which supports many florets, the assemblage of which forms an aggregate or compound flower, as in the sunflower and dandelion. The common receptacle presents a great variety of forms; as concave, convex, flat, conical, or spherical. In the fig it is concave, and constitutes the fruit. As to its surface, the receptacle is punctate, as in the daisy; hairy, as in the thistle; naked, as in the dandelion; chaffy, as in the chamomile; it is pulpy in the strawberry, and dry in most plants.

3d. Rachis, is the filiform receptacle which connects the florets in a spike, as in a head of wheat.

Our examination of the flower is now completed. We shall, in our next lecture, proceed to consider the change which takes place, after the bloom and beauty of the plant have faded. We shall find that organs, at first scarcely perceptible, begin to develop *Sometimes torus, from the Latin, signifying bed. Spadix-Receptacle--What is the proper receptacle ?--What the common?-What

is the rachis?

themselves, until the character of the fruit is fully exhibited. So in the heart of youth, the germs of virtue or vice may, for a while, be apparently dormant and inactive, but growing more vigorous and powerful, they at length unfold themselves, and reveal either a character matured into what is lovely and desirable, or marked with qualities of a disagreeable and deleterious nature.

LECTURE XV.

THE FRUIT-PERICARP-PARTS OF THE PERICARP-LINNEUS'S CLASSIFICATION OF FRUITS-MIRBEL'S CLASSIFICATION OF FRUITS.

The Fruit.

THE fruit is composed of two principal parts, the pericarp and seed. The term pericarp is derived from peri around, and karpos seed or fruit; it signifies surrounding the seed. All that in any fruit which is not the seed belongs to the pericarp.

Let us now inquire into the progress of the fruit from its first appearance in the germ to its mature state. When you analyze a flower, you often find it necessary to ascertain the number of cells contained in the germ. In making this examination, what appearance does the interior of the germ present, when exposed by cutting it horizontally? You see there minute bodies of a pale green colour, and an apparently homogeneous nature: each of these is called an ovule, and their outer covering, an ovary. These ovules, before the fertilization of the germ by the pollen, are scarcely perceptible; after this period, and the fading of the corolla, the ovules increase in size, and the embryo and other parts which constitute the seed become manifest. The ovary enlarges with the growth of the ovules; the use of this covering is not confined to the mere protection of the seeds from injury, but it is furnished with glands, which secrete such juices as are necessary for the growth and development of the ovules. As the ovary becomes more mature, it takes the name of pericarp. Pericarps in their growth become either woody or pulpy ; the latter absorb oxygen gas and throw off carbonic acid; saccharine juices are elaborated in their cellular integument. In another stage, the pulpy substance passes through a slight fermentation, the organization is disturbed, the juices sour, the pulp decomposes, and putrefaction ensues. Such is the change which you may see in pulpy fruits during their progress towards maturity and subsequent decay.

Parts of the Pericarp.

The germ being fertilized, the parts of the flower which are not necessary for the growth of the fruit, usually fade, and either fall off or wither away. The pericarp and seed continue to enlarge until they arrive at perfection. Every kind of fruit you can behold has been once but the germ of a flower. The size of fruit is not usually proportioned to that of the vegetable which produced it. The pumpkin and gourd grow upon slender herbaceous plants, while the large oak produces but an acorn.

* From ovum, an egg.

† The term fruit, in common language, is limited to pulpy fruits which are proper for food; but in a botanical sense, the fruit includes the seeds and pericarps of all vegetables.

Fruit, the two principal parts-Derivation and signification of the word pericarpOvules-Ovary-Use of the ovary-Its name in a mature state-Pulpy pericarpsGerm-Size of the fruit not in proportion to the plant that produces it.

*

In some fruits the pericarp seems to consist of three parts1st. The epicarp, the skin of the fruit, or membranous part which surrounds it, and which is a kind of epidermis;

2d. The sarcocarp,† a part more or less fleshy, corky or coriaceous, often scarcely perceptible, and covered by the epicarp,

3d. The endocarp, an internal membrane of the fruit, which lines the cavity, and by its folds forms the partitions and cells.

In the peach, for example, the skin is the epicarp; the pulpy, cellular substance which absorbs the juices of the fruit is the sarcocarp: the shell which encloses the kernel, deprived of moisture, and rendered dry and tough, is the endocarp. The endocarp is also called the putamen.

In most fruits the pericarp consists of the following parts :

1st. Valves or external pieces, which form the sides of the seed vessels. If a pericarp is formed of but one, it is univalved; the chestnut is of this kind. A pericarp with two valves is said to be biralved, as a pea-pod. The pericarp of the violet is trivalved; that of the stramonium quadrivalved. Most valves separate easily when the fruit is ripe; this separation is known by the term dehiscence.

2d. Sutures or seams, are lines which show the union of valves; at these seams the valves separate in the mature stage of the plant; they are very distinct in the pea-pod, which has two sutures.

3d. Partitions or dissepiments, are internal membranes which divide the pericarp into different cells; these are longitudinal when they extend from the base to the summit of the pericarp; they are transverse when they extend from one side to the other.

4th. Column or Columella, the axis of the fruit; this is the central point of union of the partitions of the seed vessels; it may be seen distinctly in the core of an apple.

5th. Cells, are divisions made by the dissepiments, and contain the seeds; their number is seldom variable in the same genus of plants, and therefore serves as an important generic distinction.

6th. Receptacle of the fruit, is that part of the pericap to which the seed remains attached until its perfect maturity; this organ, by means of connecting fibres, conveys to the sced, for its nourishment, juices elaborated by the pericarp.

Some plants are destitute of a pericarp, as in the labiate flowers, compound flowers, and grasses; in these cases the seeds lie in the bottom of the calyx, which performs the office of a pericarp

Linnæus's Division of Pericarps.

Linnæus made a division of fruits into nine classes, viz.: Capsule, Silique, Legume, Follicle, Drupe, Nut, Pome, Berry, and Strobilum. 1st. CAPSULE, a little chest or casket; this is a hollow pericarp which opens spontaneously by pores, as the poppy, or by valves, as the pink. The internal divisions of the capsule are called cells; these are the chambers appropriated for the reception of the seeds; according to the number of these cells, the capsule is one-celled, twocelled, &c. The membranes by which the capsule is divided into cells are called dissepiments, or partitions; these partitions are either parallel to the valves or contrary. The columella is the central pillar in a capsule; and is the part which connects the several internal partitions with the seed. It takes its rise from the recepFrom epi, upon, and karpos, fruit.

+ From sarx, flesh, and karpos, fruit. From endo, within, and karpos, fruit. Epicarp-Sarocarp-Endocarp-Valves-Sutures-Partitions or dissepiments-Column-Cel's-Receptacle of the pericarp-Pericarp sometimes wanting-Linnæus's division of pericarps-Capsule.