Suffrutiscent perennial herbs or shrubs. Leaves simple, opposite,
lineolate, usually entire, or obscurely crenulate. Flowers in terminal or
axillary, dense spikes, blue, purple, violet or purplish-white. Bracts longer
than the calyx, bracteoles linear-lanceolate. Calyx deeply 5-lobed, lobes
equal, often scarious. Corolla tube cylindrical, 5-lobed, lobes usually equal.
Stamens 4, included, 2 fertile, staminodes 2, small, shortly connate to
filaments, sometimes absent. Ovary 4-ovuled, style long, sparsely hairy, stigma
simple or slightly bifid. Capsules 4-seeded, oblong-clavate, with solid
stipe-like basal part. Seeds compressed, discoid, retinacula sharp.