Nectar guides are patterns seen in some flowers that guide pollinators to the nectar and pollen. These patterns may be visible to humans; for instance, the Dalmatian toadflax (Linaria genistifolia) has yellow flowers with orange nectar guides. ^{However in some plants, such as sunflowers, they are visible only under ultraviolet light. Under ultraviolet, the flowers have a darker center, where the nectaries are located, and often specific patterns upon the petals as well. This is believed to make the flowers more attractive to pollinators such as honeybees and other insects that can see ultraviolet. [http://webexhibits.org/causesofcolor/17C.html This page on butterflies shows an animated comparison of black-eyed Susan (Rudbeckia hirta) flowers in visible and UV light.}

External links

• Dalmatian Toadflax from the Southwest Exotic Plant Information Clearinghouse
• What do butterflies see? (speculation)

Pollination