This order comprehends the Rhubarb (Rheum), the Dock (Rumex obtusifolius), Sorrel (R. acetosa), the Buckwheat (Polygonum Fagopyrum), Persicaria (P. orientale), Water-pepper (P. hydropiper), and Knot-grass (P. aviculare). The leaves of these plants either sheath the stem with the base of their petioles, or are furnished with ochreæ, that is, with stipules which are joined together so as to form a kind of purse or boot. The flowers are inconspicuous, and the fruit is a triangular nut, retaining the calyx till it is ripe. The genera Eriogonum, Calligonum, and Kœnigia, formerly included in this order, are now formed into another, called Eriogoneæ.
ORDER CLVIII.—LAURINEÆ.—THE SWEET-BAY TRIBE.
These plants are known by their anthers, which are two or four celled, with the valves curling upwards when ripe, like those of the Berberry, and the filaments are furnished near the base with two kidney-shaped glands. The male and female flowers are distinct; the former have six, eight, or twelve stamens, and a calyx of four or six divisions united at the base. The female flowers have a one-celled and one-seeded ovary, with a simple style, and an obtuse-crested stigma; and four or more abortive stamens, furnished with glands, but without anthers. The most interesting plants contained in this order are,—the Sweet Bay (Laurus nobilis), the Sassafras-tree (L. Sassafras, or Sassafras officinale), the Cinnamon-tree (L. Cinnamomum, or Cinnamomum verum, or zeylanicum); the Camphor-tree (L. camphora, or Camphora officinarum); and the Alligator Pear (L. Persea, or Persea gratissima). All the plants belonging to this order are aromatic, either in the leaves, bark, or fruit.
Two small orders, Illigereæ and Hemandiaceæ, containing Indian plants rarely met with in England, are introduced here by some botanists.
ORDER CLIX.—MYRISTICEÆ.
The only interesting plant in this order is the Nutmeg (M. officinale, or moschata). In this plant, the fruit is pear-shaped, and it consists of a half-fleshy pericardium enclosing a jet-black stone, encircled by a fleshy orange-red arillus, which is the mace. The nutmeg is the kernel of the stone, and it is not taken out for sale till it is sufficiently ripe to rattle when shaken. The leaves are of a dark green above, and glaucous beneath; and the flowers are white, with the red pistil conspicuous in the centre. The tree is a native of Ceylon and the East Indian Islands, and it requires a stove in England.