In the genus Erica, one of the commonest species is the Besom Heath (_E. tetralix_), which is found in great abundance on moorish or boggy ground in every part of Britain. In this plant, the corollas of the flowers appear each to consist of a single petal, forming an egg-shaped tube (see _b_ in _fig._ 47), contracted at the mouth, but afterwards spreading into a four-cleft limb, through which is seen projecting the style, with its flat stigma. The corolla is, however, really in four petals, which, though they adhere together, may be easily separated with a pin. The stamens are concealed by the corolla, but the manner in which they grow is shown at _c_; and _d_ is a single stamen, showing the spurs or awns at the base of the anther, the position of which is one of the characteristics of the genus Erica in its present restricted form; _e_ is a capsule with the style and stigma attached; and _a_ is a leaf showing its revolute or curled back margin. The leaves of this species are in whorls, four leaves in each whorl, and they are ciliated, that is, bordered with a fringe of fine hairs. [Illustration: FIG. 48.—BELL-SHAPED HEATH.] [Illustration: FIG. 49.—CAPE HEATH. (_E. hispida._)] All the true Heaths bear more or less resemblance to this plant. In some, the corollas are bell-shaped, spreading out at the tip into five teeth, which inclose the stamens, as shown in _fig._ 48; and in others they are nearly globose swelling out near the calyx, and tapering to a point, beyond which the stigma and anthers project; as in the Cape Heath, called _Erica hispida_, a flower of which is shown in _fig._ 49. The leaves also differ exceedingly, in the number contained in each whorl; as in some species there are only three in a whorl, while in others they are five or six. The general features of all the Heaths are, however, the same—viz., there are eight stamens, which are generally inclosed in the corolla, though they sometimes project beyond it, as shown in _fig._ 49, and the anthers of which are two-cleft, and awned or crested at the base, while the filaments are hair-like; one style, which always projects beyond the corolla, and has a flattened stigma; a four-parted calyx and corolla which is tubular, with a four-parted limb. There are nearly two hundred species of this genus, some of which are natives of Europe, and others of the Cape of Good Hope. The moor Heaths (_Gypsocallis_) were separated from the genus Erica, by Mr. Salisbury, principally on account of the corolla being campanulate, or shortly tubular, with a dilated mouth; and the stamens projecting beyond the corolla. The filaments are also generally flat; the anthers are without awns, and distinctly in two parts; and the stigma is simple, and scarcely to be distinguished from the style. The common Cornish Heath (_G. vagans_), and the Mediterranean Heath (_G. Mediterranea_), are examples of this genus, which appears strongly marked, though, as I before mentioned, some botanists do not adopt it.