Peruvian bark. The Melia Azedarach is an invaluable anthelmintic*. Different species of Quassia, particularly the Simaruba and amara, are some of the most powerful bitter tonics of the materia medica. Kalmia latifolia and angustifolia, though hitherto scarcely employed by physicians, promise to be useful medicines, in a variety of cases. Of the former species I can speak from experiencet. Rhododendron Chrysanthum has a place in some of the European Pharmacopoeias. The Arbutus Uva ursi should be in the hands of every physician. Different species of Pyrola have been employed by physicians. To the Pyrola umbellata (Pippsissewa) great virtues are ascribed, in some parts of the UnitedStates. The Benzoin of the shops, which, for a long time, was supposed to be the produce of the Laurus Benzoin, formerly mentioned, is now ascertained to be the produce of a species of Styrax, the Styrax Benzoe. Silene virginica is said to possess the powers of an anthelmintic. Phytolacca decandra is, unquestionably, an article entitled to the attention of physicians.

MANY of the genera of the class Decandria are natives of the United-States. This tract of country is especially rich in plants of the fine order Bicornes.

FOR an illustration of the class, see Plate xvII,

See Dr. Duvall's Inaugural Dissertation. Philadelphia: 1802.

+ See Dr. Thomas's Inaugural Dissertation. Philadelphia: 1802.

For some information concerning the medical properties of several NorthAmerican vegetables belonging to the class Decandria, see different parts of my Collections for an Essay towards a Materia Medica, &c. the American Philosophical Society. Vol. v. No. vii.

See, also, Transactions of

CLASS XI.

DODECANDRIA.

TWELVE MALES.

THE twelfth class is named DODECANDRIA*. This class contains plants with hermaphrodite flowers, which, agreeably to the name of the class, ought to have twelve stamens, or male organs. It must not, however, be supposed, that all the plants of this class have the precise number of stamens which the name imports. Several of the genera have more than twelve of these sexual organs; and some of them have even less than the implied number. Thus, Bocconia has from eight to twelve, or more; Hudsonia from ten to fifteen (generally ten, rarely more than twelve); Befaria fourteen; Peganum, Nitraria, and others, fifteen; and Garcinia and Bassia, sixteen, stamens. Several of the genera have nineteen stamens, and Agrimonia has from twelve to twenty. So indeterminate is the number of the stamens of this class!

ACCORDING to Linnæus, the class in question embraces those hermaphrodite vegetables, whose flowers have from twelve to nineteen stamens, or male organs. But this is not the essential feature of the class Dodecandria. It seems to be the essential character of this class, that the stamens (or in place of them the anthers),

* From Swdɛxx, twelve.

whatever may be their precise number, are inserted into the receptaculum, or receptacle. By the place of insertion, we very readily distinguish the plants of the class Dodecandria from those of Icosandria: for in this last the stamens are inserted either into the calyx or into the petals. But it is not so easy to distinguish the plants of Dodecandria from those of Polyandria. In both, the insertion of the stamens is the same, and we shall afterwards see, that there are not a few of the plants of Polyandria which have less than nineteen or even twelve stamens*.

FROM this view of the subject, it must appear evident, that the class Dodecandria opposes a considerable difficulty to the student, in his investigation of plants, according to the principles of the sexual method. Were we to adopt the Linnæan interpretation of the class, we should rob the class Polyandria of some of its genera, and associate them with the plants of Dodecandria, with which they have much less affinity, in their general aspect, and in properties. I cannot help thinking the class Dodecandria a very exceptionable one: nor am I singular in this opinion. The learned Crantz and other writers have, long ago, entertained a similar opinion. WOULD THE SEXUAL SYSTEM SUFFER ANY INJURY BY THE TOTAL ABOLITION OF THIS CLASS? I think it would not. But where should we dispose of the genera which are now arranged under this class? In different classes, according to the number, insertion, &c. of

* Among other writers, Dr. Martyn (The Language of Botany, &c.) misleads the student by asserting, that the class Dodecandria comprehends "all those plants " which have hermaphrodite flowers with from twelve to nineteen stamens inclusive."

G

the stamens. All those genera, which have more than ten stamens, might be thrown into the class Polyandria. See POLYANDRIA.

THE class Dodecandria is subdivided into five orders, viz. MONOGYNIA, DIGYNIA, TRIGYNIA, PENTAGYNIA, and DODECAGYNIA.

MONOGYNIA.

ONE FEMALE.

THIS is the most numerous order. It embraces the following, among other genera, viz. Bocconia, Hudsonia, Asarum, Rhizophora, Garcinia, Cratæva, Halesia, Canella, Triumfetta, Peganum, Nitraria, Portulaca, Lythrum, Cuphea, and Decumaria.

DIGYNIA.

TWO FEMALES.

HELIOCARPUS and Agrimonia are referred to this order. But the latter genus should, I think, be placed in the class Icosandria.

TRIGYNIA.

THREE FEMALES.

RESEDA, the vast genus Euphorbia, Visnea, Tacca, Pallasia, and others, belong to this order.

PENTAGYNIA.

FIVE FEMALES.

THE two genera Glinus and Blackwellia are referred to this order.

DODECAGYNIA.

TWELVE FEMALES.

THE genera Sempervivum and Gastonia belong to this order.

CHARACTER.

Ir cannot be asserted, that the class Dodecandria is a natural class. The different genera which it contains have very little natural affinity to each other. Asarum