ABSTRACT
Extrafloral nectaries are plant glands located outside the flowers; they are widespread among the angiosperms, occurring in 68 of the 337 families, in 35 of 76 orders, 5 of 6 of the subclasses of dicotyledons, and 3 of the 4 subclasses of monocots. Vicia sativa L., the common vetch, is an annual herbaceous legume native to the Old World. The plants bear stipular nectaries, and in both exotic and native habitats, ants visiting these nectaries can provide protection against insect herbivores for foliage, flowers, and developing fruit. Unpredictable weather and the difficulties of excluding ants and bagging vetch plants in the field led to the conducting of that experiment under controlled greenhouse conditions. A number of chemical defenses of plants have been found to increase in response to presence of, or damage by herbivores, or both. Extrafloral nectaries attract ants and other beneficial insects that can provide biotic protection against a wide variety of herbivores.
