In this drawing (Fig. 44), you will observe the thorn (a) to remain on the stem, while the bark (b) has been peeled off. In the prickle (c) the whole appears separated from the plant. The thorns in some plants have been known to disappear by cultivation. The great Linnæus imagined that in such cases, the trees were divested of their natural ferocity and became tame. You may smile at such a strange idea, but even great minds have their weaknesses; when persons become enthusiastic in any science, they are in danger of fancying analogies or resemblances, which exist only in their own minds. A more rational opinion is given by another botanist, viz.-that thorns are in reality buds, which a more favourable situation converts into luxuriant branches. But in some cases they do not disappear even under circumstances favourable to vegetation. Thorns have been compared to the horns of animals.

4th. Glands are roundish minute appendages, sometimes called tumours or swellings; they contain a liquid secretion which is supposed to give to many plants their fragrance. They are sometimes attached to the base of the leaf, sometimes, they occur in the substance of leaves; as in the lemon and myrtle, causing them to appear dotted when held to the light. They are found on the petioles of the passion flower, and between the teeth or notches of the leaves of many plants.

5th. Stings are hair-like substances, causing pain by an acrid liquor, which is discharged upon their being compressed; they are hollow, slender, and pointed, as in the nettle.

6th. Scales are substances, in some respects resembling the coarse scales of a fish; they are often green, sometimes colour. ed, and are found upon all parts of vegetables, upon the roots of bulbous plants, and upon the stems and branches of other plants. They are imbricated upon the calyxes of most of the compound flowers. You have seen in buds, how. important the scales are to protect the embryo plant during the winter. Calyxes surround the flowers of grasses, under the name of glumes. Scales envelope and sustain the stamens and fruit of the pine, oak, chesnut, &c.

Thorns in some cases made to disappear--Glands-Stings-Scales.

Fig. 45.

7th. Tendrils, or claspers, thread-like, or filiform appendages, by which weak stems attach themselves to other bodies for support; they usually rise from the branches, in some cases from the leaf, and rarely from the leaf stalk or flower stalk. You have here the representation (Fig. 45) of a tendril. Tendrils are very important, and characteristic appendages to many plants. In the trumpet flower and ivy, the tendrils serve for roots, planting themselves into the bark of trees, or in the walls of buildings. In the cucumber and some other plants, tendrils serve both for sustenance and shade. Many of the papilionaceous, or pea blossom plants, have twining tendrils, which wind to the right and back again. Among vegetables which have tendrils, has been discovered that property, which some have called the instinctive intelligence of plants. A poetical botanist represents the tendrils of the gourd and cucumber, as "creeping away in disgust from the fatty fibres of the neighbouring olive." The manner in which tendrils stretch themselves forward to grasp some substances, while they shrink from others, is indeed astonishing, but instead of imagining that they have a preference for some and a dislike for other objects, it is much more philosophical to conclude that these effects arise from physical causes, which may, hereafter, be discovered. It has been ascertained by experiments, that the tendrils of the vine, and some other plants, recede from the light, and seek opaque bodies. The fact with respect to leaves is directly the reverse of this, for they turn themselves round to seek the light..

Some plants creep by their tendrils to a very great height, even to the tops of the loftiest trees; and seem to cease ascending only because they can find nothing higher to climb. One of our most beautiful climbing plants is the CLEMATIS virginica, or virgin's bower, which has flowers of a brilliant whiteness.

8th. Pubescence includes all down, hairs, woolliness, or silkiness of plants. The pubescence of plants varies in different soils, and with different modes of cultivation. The species in some genera of plants are distinguished by the direction of the

hairs. The microscope is sometimes necessary in determining with precision the existence and direction of the pubescence. It has been suggested that these appendages may be for similar purposes as the furs, hairs, and bristles of animals; to defend the plants from cold, and injuries from other causes.

α

Fig. 46.

9th. The Bract is a leaf among or near the flowers, different from the leaves of the plant. You may in this branch (Fig. 46) observe the difference between the real leaves (b, b) and the bract (a); the former being cordate and crenate, the latter lanceolate and entire.

In some plants, as in several species of sage, the transition from leaves to bracts is so gradual, as to render it difficult to distinguish between them, and a considerable part of the foliage is composed of the bracts. In some plants, as the crown imperial, the stem is terminated by a number of large and conspicuous bracts. These appendages are sometimes mistaken for the calyx. Bracts are either green or coloured, deciduous or persistent. The Orchis tribe have green leaf-bracts. No plants of the class Tetradynamia

have bracts.

We have, in regular order, considered the first of the two classes of vegetable organs, viz: such as tend to the support and growth of the plant, including root, stem, leaf and appendages; we are soon to enter upon the class of organs whose chief use appears to be that of bringing forward the fruit, or the organs of reproduction.

LECTURE XI.

Calyx.

We are now to consider the second division of vegetable organs, viz.: such as serve for the reproduction of the plant, usually called organs of fructification. Their names were considered, when commencing the analysis of flowers; but we are

Bract-Difference between the real leaf and the bract-Recapitulation-Se cond division of vegetable organs.

now to examine them with more minute attention, and to remark upon their different uses in the vegetable economy.

You are no doubt pleased to have arrived at that part of the plant, which is the ornament of the vegetable kingdom. Flowers are delightful to every lover of nature; a boquet or even the simplest blossom, presented by a friend, interests the heart. How many pleasant thoughts are awakened by the fresh and perfumed incense which is offered by flowers; their odour has been poetically termed the language by which they hold communion with our minds. Females are usually fond of flowers; but until recently, the greater number have only viewed them as beautiful objects, delighting the senses by their odour and fragrance; without being aware that these objects, lovely as they seemed, might be rendered doubly interesting, by a scientific knowledge of the relations and uses of their various parts. Even at the present period, there are those who spend years in cultivating plants, ignorant of their botanical characters, when a few hours study might unfold to them the beautiful arrangement of Linnæus, and open to their astonished minds a world of wonders.

Although every part of a plant offers an interesting subject for study, the beauty of the blossom, seems by association, to heighten the pleasure of scientific research. Flowers are indeed lovely, but like youth and beauty they are fading and transient; they are, however, destined for a higher object than a short lived admiration; for, to them, is assigned the important office of producing and nourishing the fruit: like them may you so improve the bloom of life, that when youth and beauty shall have faded away, your mind may exhibit that fruit, which it is the important business of the present season to protect and

nurture.

The parts of the flower, or the organs of fructification are the following,

The Calyx is frequently wanting; as in the tulip. The corolla is also wanting in many plants; as, in most of the forest trees which, to a careful observer, may seem to produce no flow. er, but the presence of a stamen and pistil, is in botany considered as constituting a perfect flower. These two organs are es sential to the perfection of the fruit; and when a flower is des

Flowers delightful-Many who cultivate them ignorant of their botanical characters-Flowers analogous to youth-Organs of fructification-Calyx, sometimes wanting.

titute either of stamens or pistils, it is termed imperfect. A flower is said to be incomplete when any of the seven organs of fructification are wanting.

The word Calyx is derived from the Greek, and literally signifies a cup; it is the outer cover of the corolla, and usually green; when not green it is said to be coloured. This organ is an expansion of the bark of the flower-stalk, as appears from its colour and texture. The calyx usually envelopes the corolla, previous to its expansion, and afterwards remains below or around its base. Sometimes the calyx consists of one leaf only, it is then called monophyllous; when it consists of several distinct leaves, it is called polyphyllous; when one calyx is surrounded by another, it is double; when one calyx surrounds many plants, it is common.

In the calyx are three parts, very distinct in calyxes which are long and cylindric; they are, 1st. the tube which commences at the base, or the top of the peduncle; 2nd. the throat, above the tube; and 3d. the mouth, or the upper and expanded part; the tube of the calyx is cylindric in the pink, and prismatic in the stramonium.

The position of the calyx with respect to the germ, offers an important mark of distinction between different genera, and also between different natural families of plants. The calyx is said to be superior when it is situated on the summit of the germ as in the apple; it is inferior when situated below the germ, as in the pink. In many plants the calyx is neither superior or inferior, but is situated around the germ.

When the calyx drops off before the flower fully expands, it is called caducous; the petals of the poppy are, at first, enclosed in a calyx of two large green leaves, but these fall off before the flower is full blown. When the calyx withers and drops off with the corolla it is called deciduous. In many plants it remains until the fruit is matured; it is then called persistent. In a pea-pod, for example, the calyx may be seen as perfect as it was in the blossom. In an apple or a pear, the dried leaves of the calyx may be seen on the tops of the fruit; this shows that the calyx was superior.

According to the divisions of Linnæus there are seven kinds of calyxes; viz.

Perianth,
Involucrum,
Ament,
Spatha,

Perianth. This term is derived from the two Greek words peri, around, and anthos, flower. This is the only real calyx or cup, as the term cup does not properly apply to the other

Description of the calyx - Parts of the calyx-- Position with respect to the germ-Duration-Different kinds of calyxes-- Perianth.