Графични страници
PDF файл

rescence clustered in a corymb; as the life-ever-lasting, bone. set, and aster.

The plants of the class Syngenesia, are in general, easily recognized at the first glance; there is something about them besides their compound character which distinguishes them from all other plants. One botanist observes, that they have a kind of “weed-like appearance, notwithstanding the beauty of their colouring ; the stems and leaves are often rough, and they seem to have been less completely reclaimed from their savage state, than most other plants, with the exception of the Cryptogamous class."*

Not many of the plants of this class are poisonous; it is remarked that milky plants are generally so, but those of this class are exceptions. The lettuce, however, contains a nar. cotic principle, and opium may be made from it. The dande. lion, the eupatorium, the chamomile, and wormwood, with many other plants of this class are valued for medicinal properties.

The Syngenesious plants are particularly abundant in our own country, and you will never find difficulty in procuring specimens. If you commence botanical studies with the flow, ers of spring, nature gradually presents you with those that are more difficult to investigate. This class, it has been before re. marked, are chiefly in blossom in the latter part of the season. Being previously prepared by a knowledge of the general principles of classification, and observations of plants, you will no doubt derive pleasure from the study of the class Syngenesia; though were you to commence a course of botany with these plants, you would feel as if thrown amidst a chaos of facts, without any clue to their classification.

* Barton.

Plants of this class easily recognized-Many are valued for medicinal properties-Found in the latter part of the season.



Fig. 122.

We shall now examine a class, in which an entirely new circumstance from any yet considered, is regarded as forming its essential character. This circumstance is the situation of the stamens upon the pistil, or the stamens appearing to grow out of that organ, In some cases the stamens appear to proceed from the germ, in others, from the style.

There is sometimes diffi

culty in deciding as to the number of stamens, for they are not here, as in the other classes, distinct organs, but in some cases mere collections of glutinous pollen.

Monandria The orders in this class, as in Monadelphia and Diadelphia, depend on the number of stamens, or of those singular collections of pollen which are called stamens. The first order of the 18th class contains such plants as have but one stamen, or two masses of glutinous pollen, equal to one stamen ; this order is divided into sections, which relate to the manner in which the anther is attached to the style; as, whether it is easily separated, whether the anther grows upon the top of the stigma, and to the shape of the masses of pollen, which are called the anther. The Orchis plants form an important part of the class Gynandria; most of these are perennial, and grow in moist and shady places ; some of them are parasites, adhering to the bark of trees by their fleshy fibrous roots. The roots sometimes consist of two solid bulbs, in other cases, they are oblong, fleshy substances, tapering towards the ends, like the fingers of the hand. These plants are in the family ORCHIDEÆ, so called from Orchis, a name derived from a Greek word, signifying an olive-berry, on account of the root being round, like that fruit. The Orchis family is not, however, confined to this one genus, but includes the ARETHUSA and several other genera. The distinguishing characters of this natural family are a corolld above the germ, 5 petals, 3 external and 2 internal. There is also in each corolla a petal-like organ, called the lip, which varies in form and direction, anthers always 1 or 2,



Class Gynandria--Orders---Orchidee-Distinguishing characters of this family.

from 1 to 4 celled, sessile, or sitting upon the side or apex of the style; the pollen is easily removed from the cells in glutin. ous masses ; the styles are simple, with viscous stigmas of va. rious forms and positions. The capsules are 1 celled, 3 valved, 3 keeled; seeds are numerous and dust-like, clasping the stem like the leaves of grasses. The stems or scapes are simple, undivided, and the flowers are arranged in spikes or racemes.

The family Orchideæ is in the 4th class of Jussieu's method, having monocotyledonous seeds, and stamens epigynous, or above the germ. The flowers of this family are remarkable for their irregular, picturesque, and we might add, grotesque appearance; some present the figure of a fly, others of a spider, a bird, and even of the human figure. It would seem too, that the freaks of these vegetable beings are not designed for our observation, for they are as curious in their choice of habitations as in their external forms; preferring wildness, barren. ness and desolation to the fostering care of man, or the most luxuriant soil. It is in forests of the equatorial regions, that these plants appear in the greatest perfection. The aromatic vanilla is obtained from the fruit of a climbing orchis of those regions.

The Orchis genus has a nectary in the shape of a horn ; its corolla is somewhat ringent, the upper petal vaulted, the lip is spreading, the 2 masses of pollen are concealed at the sides, by little sacs, or hooded hollows of the stigma.

Fig. 122 represents a flower of this genus; a, shews the two masses of pollen, brought out from the cells of the anther which is attached to the pistil.

Diandria. The 2d order contains the ladies' slipper (CYPRIPEDIUM); the nectary or lip is large, inflated, and resembles a slipper. We have several species of this curious plant, some of which are yellow, some white, and others purple.

Pentandria. The 5th order contains the milk-weed (ASCLEPIAS), which by some has been placed in the fifth class, on the supposition that the stamens did not proceed from the pistil. In order to assist you to understand these flowers, we will present you with a very plain and simple description, from a manuscript belong. ing to an American botanist,* who has devoted many years in attention to scientific pursuits, and has particularly examined into the character of the plants we are now considering. He says, “ I select the milk-weed for exercising you in the Gram

* Professor Eaton.

OrchisLadies' slipper-Order Pentandria.

mar of Fructification, because it will lead you into a very nice investigation of that kind of flower whose anthers produce glu. tinous pollen; and I now apprize you, that the stamens are generally obscure, and difficult to ascertain correctly in such cases, particularly in the flowers of the Orchis tribe.

« Take one of those heads of flowers from the milk-weed (ASCLEPIAS), which are so common in the months of June and July; you will perceive that each flower grows upon a little stalk, and that all these stalks proceed from the same centre, like the braces of an umbrella ; which answers to the definition given of an umbel inflorescence.

“ The most conspicuous parts of a single flower, are five upright substances, and five petals reflexed and lying down close to the stem; lift

up those petals, and you will find a calyx con. sisting of five small narrow leaves.

6. You will now have ascertained that the inflorescence is an umbel, that the calyx consists of five leaves, and the corolla of five reflexed petals.

“ As the five upright substances, with a little horn in the cen. tre of each, have not the appearance of stamens, although they are next in course to the petals, you may at first be at a loss what to call them; but I will here give you Linnæus' name for every thing, whether inside or outside of the corolla, if it be neither calyx, stamen, nor pistil, of whatever form and size it may be ; he, having found that such parts generally secrete a sweet liquid, calls them all by the general name nectaries ; such as the shoe part of the ladies' slipper, the spur of the nas. turtion, &c. Now pull off all the nectaries, and examine the part which they encircled. You will observe five shelly projections between where the nectaries stood; between these are seeds lying very close, which you must peel off carefully with a sharp pointed knife, so as not to disturb what is under them. You will probably find some difficulty in effecting this at the first trial, but you cannot proceed in your examination until it be accomplished.

“Next, examine what is left with your magnifying glass, though you may see the parts without a glass ; you will discover a lobe hanging down from each side of the five shelly projections, resembling bees' wax in appearance; these are the anthers with glutinous pollen ; as the two lobes hang to the branches of a single stamen, though very unlike stamens in other cases, they are properly the double anther of a single stamen. The thick substance from which the stamens proceed, is the stigma, consequently, the milk-weed is placed in this class, GYNANDRIA ; the orders in this class are distinguished

Eaton's description of the milk-weed.

like the preceding classes, consequently, the five stamens place it in the order PENTANDRIA. The large thick stigma has the appearance of a germ or pericarp; but if you pull off the stigma, you will discover two pericarps under it, of a different structure from that of the stigma; perhaps you will never meet with a stigma in any other flower, so large in proportion to its other parts as in the milk-weed. The anthers are pressed close to the side of the stigma by the valves or scales, and the glutinous pollen probably is absorbed by it; by which means the seed is fertilized, as in cases where the pollen is a dry pow. der. The manner in which either kind of pollen operates upon the stigma, is totally inexplicable; we know nothing more of the subject, than that no seed is ever perfected without it, in any species of vegetables.”

No farther remarks on the character of this plant could be of use, after the clear and plain description just given; you will have no difficulty in procuring specimens of this plant for analy. sis; a variety of species are in flower in June and July.

The Apocynum or dogsbane, with some other genera which were formerly placed in the 5th class, are now classed here.

Hexandria. The 6th order contains the Virginia snake-root (ARISTOLOCHIA serpentaria)ça perennial plant, with brown fibrous roots; it is found in shady woods, from New England to Florida : the root is highly valued in medicine; it possesses an aromatic smell, somewhat similar to spruce. It is said to have been found, by a chemical analysis, to contain "pure camphor, a resin, a bitter extractive, and a strong essential oil.”*

It was used by the Indians as a remedy for the bite of a snake ; from this circumstance is derived its name. This plant has medical properties unlike the POLYGALA senega, or Seneca snake-root, and the mistaking one for the other might, in critical stages of disease, be attended with fatal consequences.

Decandria. In the 10th order we find the wild ginger (ASARUM); this is a native plant, so low that its flowers are almost concealed in

Rafinesque's Medical Flora. + A physician prescribed for an infant the Seneca snake-root (POLYGALA senega), as a medicine in case of extreme sickness; an ignorant apothecary sent in answer to the prescription, the Virginia snake-root (ARISTOLOCHIA serpentaria). The physician had fortunately remained to inspect the medicine which he had ordered, and the mistake was seasonably discovered; this instance shows the importance of botanical knowledge, particularly in those who attempt to deal in medicine, had the mother of the child understood botany, the mistake would have been discovered although the physician had not been present.

本 *

Order Hexandria-Virginia snake-root-Seneca snake-root-Wild ginger.

« ПредишнаНапред »