Tecoma stans was introduced in Brazil for ornamental purposes and occurs both as a cultivated or sub-spontaneous plant. This study aims to evaluate the allelopathic potential of the aqueous leaf extract of Tecoma stans on the germination and root development of three plant species: Lactuca sativa L. (lettuce), Handroanthus ochraceus (Cham.) Mattos (ipe), and Medicago sativa L. (alfalfa). The aqueous leaf extract of Tecoma stans caused strong inhibition on lettuce germination. The seedlings of lettuce and alfalfa had their root development reduced by 75% and 30%, respectively. There was no effect of the extract on the germination or root development of ipe. Also, the germination rate of the three species tested was reduced. Micromorphological changes were observed in the root apex of lettuce seedlings.
allelopathic potential; germination; bignoniaceae