Herbaceous plants, remarkable for the beauty of their foliage rather than their flowers. Leaves pinnatifid or bipinnatifid and toothed. Flowers in leafy spikes terminating the stem. Calyx unequally 4-lobed, sometimes spinescent. Corolla having only one lip, the inferior, developed. Stamens 4. Cells of the capsule 2-seeded. The three or four species described are from the shores of the Mediterranean Sea. "AkaavOa signifies spine or thorn, and was applied to the prickly species by the ancients. It is recorded that the foliage of these plants furnished the idea for decorating the capitals of the Corinthian order of architecture.

1. A. spinosus (fig. 196). Bear's Breech. - Stems about 3 feet high. Leaves and bracts very prickly. Flowers purplish and white, appearing in Summer. A. spinosissimus scarcely differs, but the flowers are larger.

2. A. mollis. - This is a similar plant, but the teeth of the leaves, though acute, are not prickly. A. latifolius is a variety of this. Flowers white, pink or pale blue. A. longifdlius is distinguished by its longer leaves, narrower in outline, and crimson flowers.

Thunbergia alata is a very handsome perennial from India and Africa, which is ordinarily treated as annual. It is a twining plant with hastate petiolate leaves, the petioles winged, and solitary axillary pedunculate nearly regular flowers with a broad spreading limb. They are variously coloured: either white, buff, pale yellow or orange, with a purplish-black centre, or uniformly orange or white.

Fig. 196. Acanthus spinosus. (1/4 nat. size.)

Fig. 196. Acanthus spinosus. (1/4 nat. size.)

Dianthera Americana, Water Willow, is a pretty North American aquatic perennial 1 to 2 feet high with linear-lanceolate glabrous leaves and axillary long-stalked dense spikes of purplish bilabiate flowers. It is peculiar in having the anther-cells of the two stamens placed one below the other.