is referred to the order Sarmentaceæ; Garcinia and Halesia to the order Bicornes; Lythrum to Calycanthema; Portulaca and Sempervivum to Succulentæ. Triumfetta, and Heliocarpus belong to the thirtyseventh of Linnæus's natural orders, the great order Columnifera, which will be more particularly considered afterwards. Euphorbia, with a number of other genera, belongs to Linnæus's thirty-eighth order, Tricocca. In the system of Mr. De Jussieu, the genus Euphorbia gives name to a particular order, Euphorbia.

FEW of the classes of the sexual system are of so little consequence to mankind, in a medical point of view as the class of which I am speaking. Some of the plants, however, which it embraces, are endued with useful medical properties. Different species of Asarum, or Asarabacca, are employed as sternutatories, and as emetics. The leaves of Asarum europæum, or Common Asarabacca, constitute the basis of the pulvis sternutatorius of some of the foreign Pharmacopoeias. Asarum canadense, very improperly called Coltsfoot, is sold in the market of Philadelphia, as a remedy for hoopingcough. The root of this species has an agreeable aromatic taste: hence one of the more common names of this plant, Wild-Ginger. The Canella alba of the shops is the bark of a West-India vegetable of the same name. Lythrum Salicaria has been recommended* as a remedy in dysenteries. Different species of Euphorbia, or Spurge, are employed in medical practice. It was, at one time, supposed, that the Ipecacuanha of the shops is the root of Euphorbia Ipecacuanha. But it is now ascertained, that the most useful of the vegetable emetics

By Threlkeld, De Haen, and other writers.

is the root of a Pentandrous plant, which was formerly mentioned. Euphorbia Ipecacuanha is, however, employed as an emetic, in some parts of the United-States.

As to Agrimonia Eupatoria, or Agrimony, which was once a celebrated remedy, I believe few persons, nowadays, repose much confidence in it, notwithstanding the high encomiums which it received from that singular and multifarious character, Sir John Hill.

Or the genera which I have mentioned, the following are known to be natives of the United-States: viz. Hudsonia, Asarum, Halesia, Decumaria, Triumfetta, Portulaca, Lythrum, Cuphea, Agrimonia, and Euphorbia.

FOR an illustration of the class Dodecandria, see Plate xxx.

CLASS XII.

ICOSANDRIA.

TWENTY MALES.

THE twelfth class is denominated IcoSANDRIA*. This class embraces those hermaphrodite flowers which

* From Exooi, twenty.

are furnished with twenty or more stamens, which are inserted into the calyx, or into the inner side of the pe. tals. By this last mentioned circumstance, and not by the mere number of the stamens, is the class Icosandria distinguished from the class Polyandria, which is next to be treated of. Many Polyandrous plants are not furnished with more stamens than the plants of the class Icosandria. On the contrary, we shall afterwards see, that not a few of the genera which Linnæus has arranged in the XIIIth class of his system, have constantly less than twenty stamens. Here, then, we once more enter into a region of difficulty with respect to the discrimination of the classical characters of the universally re. ceived system of Linnæus. How are the classes Icosandria and Polyandria to be distinguished from each other?

I HAVE just said, that in the plants of the class Icosandria, the stamens, whatever may be their number, are inserted into the calyx, or into the sides of the petals. But in the plants of the class Polyandria, the stamens are inserted into the receptaculum, or receptacle, of the flower. This is a nice and very interesting character in the discrimination of these two classes. We shall afterwards see, how important, and how necessary to be attended to, it is in our endeavours to investigate the properties of Icosandrous and Polyandrous plants.

THERE is still another character by which the class Icosandria may be distinguished from Polyandria. The plants of Icosandria have a concave calyx, or flower-cup, which is composed of one leaf, to the inner side of which the petals are fastened by their ungues, or claws.

"To

"CONFOUND THIS CLASS WITH POLYANDRIA IS ABO"MINABLE." See POLYANDRIA.

THE class Icosandria is subdivided into five orders, viz. MONOGYNIA, DIGYNIA, TRIGYNIA, PENTAGYNIA, and POLYGYNIA.

MONOGYNIA.

ONE FEMALE.

THIS first order contains the following genera, viz. Cactus, Eugenia, Philadelphus, Leptospermum, Fabricia, Metrosideros, Psidium, Myrtus, Punica, Robinsonia, Calyptranthes, Eucalyptus, Foetidia, Sonneratia, Amygdalus, Prunus, Chrysobalanus, Plinia, Banara, Antherylium, and Scolopia.

DIGYNIA.

TWO FEMales.

To this order, as yet, only two genera are referred: viz. Crataegus, and Waldsteinia. The former genus is by no means constantly digynous. Even the same species is very inconstant, as to the number of its pistils.

• Professor Martyn.

TRIGYNIA.

THREE FEMALES.

THIS order contains only two entire genera, viz. Sorbus and Sesuvium.

PENTAGYNIA.

FIVE FEMALES.

THE genera Tetragonia, Mespilus, Pyrus, Mesembryanthemum, Aizoon, and Spiræa, belong to this order. One species of Spiræa, S. opulifolia, is referred by Willdenow, to the order Trigynia. But this species is by no means constant in the number of its styles.

POLYGYNIA.

MANY FEMALES.

THE genera Rosa, Rubus, Tormentilla, Dryas, Fragaria, Potentilla, Geum, Comarum, and Calycanthus, belong to this order.

CHARACTER.

ALTHOUGH the class Icosandria cannot be said to be

a natural class, in the strict sense of the term, it will not