Tecoma stans (L.) Juss. ex H.B.K., a shrub or small tree in the Bignoniaceae, is a widely distributed polymorphic complex of the Western Hemisphere tropics and subtropics, and is commonly planted as an ornamental throughout the tropical world. Winter temperature limits its poleward distribution. The species is characteristic of rocky slopes, often limestone outcrops, but also alluvial and other substrata as long as drainage is excellent. In arid regions it occurs in climax xerophytic shrub or thorn forest communities, while in humid areas it is common mainly in deforested and other disturbed sites since it behaves as a heliophyte. The large yellow funnel-form flowers are pollinated by hummingbirds and perhaps also by some insects. The sensitive lobed stigma may favor cross-pollination, and neither dichogamy nor autogamy are usually shown. Extra-floral calyx nectaries which attract ants seem ineffective against corolla-base piercers. A low percentage of fruit is commonly set, drought and pollination failure probably being contributing factors. The pendant capsules contain many paper-thin wind-dispersed winged seeds, which have moderately high viability undiminished even after four years, and no dormancy. The strongly tap-rooted seedlings are often abundant in disturbed sites. The leaflet size class is microphyllous, and the species varies from evergreen to winter deciduous. It responds to drought partly by leaf abscission, but also by survival of prolonged permanent wilting, unusual for a thin-leaved mesomorph. Stump-sprouting is vigorous following cutting or fire, and browsing occurs in heavily-used pastures. No insect parasites or diseases are generally limiting.