Herbs, shrubs, rarely erect or lianas. Leaves simple, opposite,
ovate to lanceolate, cordate or hastate, usually lobed or toothed, rarely
subentire. Cystolith absent. Flowers in terminal, pendulous, racemes or
solitary or pairs in the axils of ordinary leaves, blue, yellow, orange-yellow,
red or white. Bracts 2, foliaceous, bracteoles spathaceous, enclosing flower
buds, mostly persistent. Calyx very short, cup-like, with 10-16 subulate teeth
or reduced to a rim. Corolla funnel-form, 5-lobed. Stamens 4, all fertile.
Pollen spiraperturate. Ovary seated on disc, 2-locular, 2 ovules in each.
Capsules depressed-globose below, abruptly beaked in upper part, 4-seeded,