Pollination and flower diversity in scrophulariaceae

The flowers of the Scrophulariaceae show a great diversity in form, especially of the corolla. The most common pollinators are bees collecting nectar, pollen, or oil; other pollinators are moths and butterflies, hummingbirds, syrphid flies, and (in one case) ants. The occurrence of bell-shaped corollas in most tribes of the Scrophulariaceae and in related families indicates that this is the basic (ancestral) flower form. Derived from it are narrow tubular corollas, wide flaring ones, corollas closed to unsuitable visitors by a palate (an upcurving of the tube), corollas forming a keel around the style and anthers either on the upper or lower side of the flower, corollas inflated to form a balloon, and corollas with one or two spurs. Convergences due to selection by the same or similar pollinators limit the usefulness of most of these floral features in analyzing the systematic relationships of the tribes of the Scrophulariaceae. Nevertheless, their diversity of forms exemplifies the evolutionary potential of fused perianth parts.