Attractants and rewards are required for:

Insect pollinated plants provide rewards as edible pollen grain and nectar. While some plants also provide a safe place for deposition of eggs. Insect pollination is a form of pollination whereby pollen of plants, especially but not only of flowering plants, is distributed by insects. Flowers pollinated by insects typically advertise themselves with bright colours, sometimes with conspicuous patterns leading to rewards of pollen and nectar; they may also have an attractive scent which in some cases mimics insect pheromones.

Both hydrophily (water pollination) and anemophily (wind pollination) do not require rewarding flowers. Cleistogamous flowers are self-pollinated.