ORDER CIII.—RUBIACEÆ. (See Chap. V. P. [85].)
This order is divided into thirteen sections, most of which have been already described. In all the species the tube of the calyx adheres to the ovary, which is crowned with a fleshy cup, from which arises the single style; and the petals are united at the base, and attached to the upper part of the tube of the calyx.
ORDER CIV.—OPERCULARIEÆ.
Exotic weeds, formerly included in Rubiaceæ.
ORDER CV.—VALERIANEÆ.—THE VALERIAN TRIBE.
No person can ever have been in the neighbourhood of Greenhithe, in Kent, without having observed the red Valerian, which grows in such abundance on the steep banks of the chalk-pits in that neighbourhood; and probably still more of my readers will be familiar with the common wild Valerian, or All-heal, which is found in moist places, generally among sedges, in every part of England. Another species of the same genus is common in Scotland, so that the name of Valerian is familiar to all persons who know anything of British plants. Common as these plants are, however, probably most of my readers are unaware of the very curious construction of their flowers; or of the very great variety exhibited by the different species. The genus Valeriana is, indeed, one which presents a remarkable instance of variety of construction, united with a similarity of form which makes all the species recognisable at a single glance. In all the species, the corolla is funnel-shaped, with a long tube, and a five-lobed limb. In the red Valerian (V. rubra), the lower part of the tube is drawn out into a spur; and on this account the plant is sometimes called the spurred Valerian, and it has been placed by De Candolle in a new genus, which he called Centranthus. The other species of Valerian have the tube of the flower gibbous, that is, much larger on one side than on the other. In all the calyx is tubular, with the limb curiously rolled, so as to form a rim or crown to the fruit, like that on the heads of basket-women. When the flowers drop, the fruit, which is one-celled and one-seeded, and which adheres closely to the tube of the calyx, begins to swell, and as it does so the limb of the calyx gradually unrolls, till at last, when the fruit is ripe, it forms a sort of feathery tuft to waft it away. The leaves of plants of this genus vary exceedingly, even on the same plant; but generally those of the red Valerian are lanceolate; those of V. dioica are pinnatifid; those of the wild Valerian (V. officinalis), pinnate; and those of the garden Valerian, the kind found in Scotland, (V. pyrenaica,) are cordate. The flowers of V. dioica are male and female, and are found on different plants. The principal other genera in this order are Valerianella, the Corn Salad or Lamb’s Lettuce; and Fedia, the Horn of Plenty.