FLORA AUSTRALIENSIS.
Class I. DICOTYLEDONS.
Stem, when perennial, consisting of a pith in the centre, of one or more concentric circles of woody tissue, and of the bark on the outside. Embryo with two cotyledons, the young stem in germination proceeding from between the two lobes of the embryo or from a noth at its summit.
The above characters are the most constant to separate Dicotyledons from Monocotyledons; these two great classes have, however, each a peculiar habit, which in most cases is easily recognized. All Australian trees and shrubs, except Palms, a few Ferns, and Bamboos, and a few others with linear grass-like leaves, are Dicotyledons; so also are almost all plants with opposite, or whorled, or netted-veined leaves, or with the parts of the flower in fours, fives, or eights, or with indefinite stamens, all these characters being very rare in Monocotyledons.
(The following list of Orders contained in this first volume is intended to show the arrangement adopted. The characters given are not absolute, nor without exception, and are inserted for the purpose of calling attention to one or two of the most striking or most important features of each Order. In some cases where Order is represented in Australia only by some anomalous gems, its exceptional character is placed in parenthesis. An analytical key to the Orders will be given at the close of the work.)
SUBCLASS I. POLYPETALÆ.
Petals several, distinct (wanting in a few genera, very rarely united).
Series I. Thalamifloræ.—Torus small or elongated, rarely expanded in a disk. Ovary superior. Stamens definite or more frequently indefinite.
Alliance (Cohors) I. Ranales.—Stamens indefinite, or if definite, opposite the petals. Carpels distinct or united at the base only, superior, or rarely enclosed in a fleshy torus. Embryo small, in a fleshy albumen.
(Carpels united in Eupotamia and Nymphæa. Embryo large, without albumen in some Menispermaceæ and in Nelumbium.)
I. Ranunculaceæ. Herbs with radical or alternate leaves, or climbers with opposite leaves. No stipules. Sepals usually coloured and deciduous. Petals in a single series or none. Stamens indefinite. No arillus.
II. Dilleniaceæ. Shrubs or undershrubs with alternate leaves. No stipules. Sepals usually herbaceous and persistent. Petals in a single series. Stamens usually indefinite. Seeds with an arillus or strophiola.
