ORDER LXXXIX.—PORTULACEÆ.—THE PURSLANE TRIBE.
The ornamental plants belonging to this order, are all included in the genera Calandrinia, Portulaca, Talinum, and Claytonia; and those belonging to the first two of these genera have very showy flowers. In all the species the flowers have a distinct calyx, generally of only two sepals, which remains on till the seeds are ripe; and a corolla of five regular petals, which close in the absence of the sun. Each flower has numerous stamens, and a single style with a broad-lobed stigma which, is succeeded by a dry, one-celled capsule, with a central placenta, to which are attached numerous seeds. The capsule opens naturally when ripe by splitting into three or four valves. But the most distinctive mark by which plants belonging to this order can be distinguished from others with similarly shaped flowers, is their remarkably thick fleshy leaves, an example of which may be seen in the leaves of Calandrinia discolor; and these succulent leaves render all the ornamental plants belonging to the order peculiarly liable to be destroyed by frost or damp. Some botanists make a second order out of the plants usually included in Portulaceæ, to which they give the name of Fouquieraceæ.
ORDER XC.—PARONYCHIEÆ.
Weedy plants, containing among other genera, Knot-grass (Illecebrum), and Strapwort (Corrigiola). The new order Scleranthaceæ has been separated from this; and it takes its name from the British weed, Knawel (Scleranthus).
ORDER XCI.—CRASSULACEÆ.—THE HOUSELEEK TRIBE.