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INTRODUCTION TQ BOTANY.'

DIADELPHIA contains four orders.Pentandria. Examp.— Monnieria.Hexanuria. Examp.— Fumuria, Fumitory.Octandria. Examp.— Polygala, Milkwort.

Decandria. Examp.— Spartium, Common Broom; Lupinus, Lupin;Glycyrrhiza, Liquorice ; Medicago, Medic; Pisum, Pea.

In the class POLYADELPHIA there are four orders, called from thenumber of stamens in each set.

Pentandria. Examp.— Abroma, Theobroma.

Dobecandria. Examp___ Monsonia.

Icosandria. Examp.— Citrus, Orange-tree.

Poeyandria. Examp.— Hypericum, St. John's Wort; Melaleuca.

The genera in this class are hut few ; and, in fact, it could easily bedispensed with altogether, as all of the flowers would agree with theclass Pohjandria.

The class SYNGENES1A contains six orders. In this class will befound a difference in structure from any of the preceding, as it will beseen that in some of the flowers composing it the florets are not allfurnished with stamens; others that have these parts are destitute ofthe style or pistil, and consequently, from their being thus incom-plete, are barren, and do not produce seed : but this is to be understoodto extend only to a certain part of the florets composing a flower; for,notwithstanding this circumstance, it occurs in all the orders after thefirst; yet there are also perfect florets which will produce seed, so thateach plant is renewed from that natural source.

It will be supposed that, if the pupil has paid attention to the cha-racters of the preceding classes and the orders that have become theobject of his investigation, he will readily distinguish the parts of whicheach Syngenesious plant is composed, and necessarily reduce it to itsproper place in the system.

The first order, Poiygamia jEqualis, has all the florets fertile, andconsequently forming a flower completely regular, i. e. without theappearance of rays. The Dandelion (Leontodon) is an example; alsoiSonchus, Sowthistle; and Cardials, Common Thistle. The pappus, ordown, on the seeds of this class forms a round head, and makes a beau-tiful appearance: as all the florets are equally fertile, so is each suc-ceeded by a perfect seed. Examp.— Scorzonera, Viper's Grass; Ci-ckorium, Chicory; Onopordon, Cotton Thistle.

The second order, Polygamia Sopekfi.ua, is distinguished by theflorets of the disk having perfect stamens and pistils ; and those of theradius, pistils only. Examp.— Anthemis, May Weed ; Bellis, Daisy;Senecio, Groundsel; Inula, Elecampane; Chrysanthemum, Ox-eyeDaisy ; Gnaphalium, Cudweed.

The third class is Polygamia Frustranea. The florets of the centrein this order are perfect, and produce seed ;and those of the circumfe-rence are altogether imperfect, not having any visible parts of fructi-