BIGNONIACEAE (Trumpet Creeper Family)

Plants trees, shrubs, or lianas, sometimes with tendrils. Leaves opposite or whorled, lacking stipules, simple or compound. Inflorescences various, axillary or terminal. Flowers perfect, hypogynous, without subtending bracts. Calyces actinomorphic or zygomorphic, splitting irregularly into 2 lobes or 5-lobed, the lobes sometimes reduced to teeth or nearly absent. Corollas zygomorphic, 5-lobed, sometimes appearing 2-lipped. Stamens 2 or 4, the filaments fused to the corolla tube, the anther sacs often appearing relatively distinct from each other and spreading, sometimes attached asymmetrically with one sac appearing terminal and the other appearing somewhat lateral. Staminodes sometimes also present, 1–3, particularly in some genera with only 2 functional stamens. Pistil 1 per flower, of 2 fused carpels. Ovary superior, with 2 locules, the placentation usually axile. Style 1 per flower, the stigma 1, with 2 deep flaplike lobes. Ovules numerous. Fruits capsules, linear-elongate, 2-valved, longitudinally dehiscent. Seeds variously shaped, flattened, winged. One hundred to 120 genera, about 800 species, cosmopolitan, but most diverse in tropical and subtropical regions, especially northern South America.

In the tropics, the Bignoniaceae are among the most important families of lianas. A number of lianas, shrubs, and trees in several genera are cultivated as ornamentals, especially in the southern states.

The genus Paulownia, which was included in the Scrophulariaceae by Steyermark (1963) and in the Bignoniaceae by Cronquist (1981, 1991), is segregated into its own family in the present work, for reasons discussed in the treatment of Paulowniaceae. Paulownia is distinguished most easily from the superficially similar Catalpa by its bluish purple corollas and ovoid fruits.