Nectar guide
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Nectar guides are patterns seen in some flowers that guide pollinators to the nectar and pollen.
These patterns are sometimes visible to humans; for instance, the Dalmatian toadflax (Linaria genistifolia) has yellow flowers with orange nectar guides.[1] 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 honey bees and other insects that can see ultraviolet. This page on butterflies shows an animated comparison of black-eyed Susan (Rudbeckia hirta) flowers in visible and UV light.
The ultraviolet color, invisible to humans, has been referred to as bee violet, and mixtures of ultraviolet with shorter (yellow) wavelengths are called bee purple by analogy with purple in human vision..[2]
[edit] References
- ^ "Dalmatian Toadflax (Internet Archive)". http://web.archive.org/web/20070317043446/http://www.usgs.nau.edu/swepic/factsheets/lidasf_info.pdf.
- ^ Charles D. Michener (1974). The Social Behavior of the Bees: A Comparative Study. Harvard University Press. ISBN 0674811755. http://books.google.com/books?id=aordrL_D-30C&pg=PA17&dq=%22bee+purple%22&lr=&as_brr=3&ei=ZBKAR7fHHoqqswOS9sGcCw&sig=B6QR7Yzx2_e13-kb-reuNknai7g.
[edit] External links
- Dalmatian Toadflax from the Southwest Exotic Plant Information Clearinghouse.
(See archived version on the Internet Archive -- accessed on 2009-03-17). - What do butterflies see? (speculation)
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