Herbs, shrubs, or vines, often twining. Leaves simple, opposite and decussate, often with cystoliths that appear as streaks on the blade, margins usually entire but sometimes toothed or lobed, stipules absent. Flowers perfect, zygomorphic to nearly actinomorphic, in spicate, racemose, or cymose inflorescences, each flower subtended by often large and brightly colored bracts; calyx usually 4-5-lobed, in Thunbergia 5-16-lobed or the lobes suppressed; corolla tubular, 2-lipped or 5-lobed; stamens 2 or 4 in pairs, inserted on the corolla alternate with the lobes, sometimes 1 or more reduced to staminodes; anthers dithecal, opening by longitudinal slits; ovary superior, 2-carpellate, placentation axile. Fruit a 2-celled capsule, usually dehiscing explosively. Seeds on small hooked stalks (modi­fied funiculus) that ejects the seeds from the capsule (exc. Thunbergia), embryos usually large, endosperm absent.

A family comprising 250 genera and 2,500 species, widespread in tropical regions, with only a few species in temperate regions. Represented in Hawai‘i by 14 naturalized species in 8 genera.

Odontonema strictum (Nees) Kuntze, with oblong, wavy margined leaves, flowers in erect, dense inflorescences, tubular crimson corollas up to 2.5 cm long, stamens 2, staminodes 2, and fruit a clavate capsule, is cultivated in Hawai‘i. It is sometimes observed in disturbed areas that do not obviously represent cultivated plants, at least on Kaua‘i, 0‘ahu, and Hawai‘i; however, none of the plants in the field or represented by specimens that we examined appear to set fruit. Therefore, this species does not appear to be natural­ized in Hawai‘i.