ORDER CXLIII.—VERBENACEÆ.—THE VERVAIN TRIBE.
The genus Verbena is well known, from the many beautiful species now common in every greenhouse. The fruit is two or four celled, and a drupe or a berry, and the calyx of the flowers is tubular, and persistent round it; but the corolla is deciduous, and falls off long before the fruit is ripe. In the genus Verbena the calyx is tubular, with five distinct angles, ending in five teeth. The corolla has a cylindrical tube nearly double the length of the calyx, and a flat limb divided into five unequal segments, which are wedge-shaped and notched, the central one of the lower three appearing to have been slightly pinched; the throat of the corolla is hairy. There are four stamens, two longer than the others, the anthers having two widely-spreading lobes, as in the Labiatæ. The style is slender below, and thickest in the upper part; and the stigma is two-lobed. The leaves are opposite, and furnished with stipules The flowers form a corymb in the Scarlet Verbena, and a spike in some of the other kinds, which elongates gradually as the flowers expand. The principal other genera are Clerodendron, or Volkameria, Vitex (the Chaste-tree), Lantana, Aloysia (the Lemon-scented Verbena), and Tectona (the Teak) which is so much used in the East Indies for ship-building.
ORDER CXLIV.—MYOPORINÆ.
Australian and Polynesian plants, nearly allied to Verbenaceæ. The principal genera are Myoporum and Avicennia, the White Mangrove of Brazil.
ORDER CXLV.—ACANTHACEÆ.
These plants are known by the elastic opening of the capsules, which are two-celled, and the hooked points of the seeds by which they are attached to the placenta. The calyx remains on the ripe fruit, but in most of the plants it is so extremely small as to be inconspicuous, and its place is supplied by three large leafy bracts. The corolla varies considerably, being sometimes two-lipped as in Justicia, sometimes funnel-shaped as in Ruellia, and sometimes campanulate, with a spreading five-cleft limb, as in Thunbergia. There are only two stamens in Justicia and some of the other genera, but in Thunbergia, Acanthus, and Ruellia, there are four of unequal length, inclosed within the throat of the corolla. The ovary is imbedded in the disk, and it is two or many seeded; the style is simple, and the stigma one or two lobed.