Why is a stigma sticky?

A flower's stigma features a sticky surface in order to efficiently trap and prepare the pollen for fertilization. This sticky substance that resembles wax and covers the stigma also rehydrates the dry grains of pollen before they enter the ovary.

Sometimes, the stigma, a surface located at the top of a flower's pistil, also traps pollen using hairs, flaps and other specially designed surfaces. Depending on the type of flower, stigmas vary in shapes and sizes. While some stigmas are long and thin, others feature round shapes and feathered or stringy borders. The stigma connects to the ovary though the style, a part of the flower that resembles a long tube.