Nectar guides are markings or patterns seen in

flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechanis ...

s of some

angiosperm Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants ...

species, that guide pollinators to their

rewards Reward may refer to: Places * Reward (Shelltown, Maryland), a historic home in Shelltown Maryland * Reward, California (disambiguation) * Reward-Tilden's Farm, a historic home in Chestertown Maryland Arts, entertainment, and media * "Reward ...

. Rewards commonly take the form of

nectar Nectar is a sugar-rich liquid produced by plants in glands called nectaries or nectarines, either within the flowers with which it attracts pollinating animals, or by extrafloral nectaries, which provide a nutrient source to animal mutualist ...

pollen Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametop ...

, or both, but various plants produce oil, resins, scents, or waxes. Such patterns also are known as "pollen guides" and "honey guides", though some authorities argue for the abandonment of such terms in favour of ''floral guides'' (see for example Dinkel & Lunau). Pollinator visitation can select for various floral traits, including nectar guides through a process called pollinator-mediated selection. These patterns are sometimes visible to humans; for instance, the Dalmatian

toadflax Toadflax is the common name of several related genera of plants in the family Plantaginaceae, including: * '' Anarrhinum'' * ''Antirrhinum'', also called Snapdragon * '' Chaenorhinum'', native to Turkey and the Mediterranean * '' Cymbalaria'' * ' ...

(''Linaria genistifolia'') has yellow flowers with orange nectar guides. However, in some plants, such as

sunflower The common sunflower (''Helianthus annuus'') is a large annual forb of the genus ''Helianthus'' grown as a crop for its edible oily seeds. Apart from cooking oil production, it is also used as livestock forage (as a meal or a silage plant), ...

s, they are visible only when viewed in

ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiation ...

light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 t ...

. 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

pollinator A pollinator is an animal that moves pollen from the male anther of a flower to the female stigma of a flower. This helps to bring about fertilization of the ovules in the flower by the male gametes from the pollen grains. Insects are the m ...

s such as

honey bee A honey bee (also spelled honeybee) is a eusocial flying insect within the genus ''Apis'' of the bee clade, all native to Afro-Eurasia. After bees spread naturally throughout Africa and Eurasia, humans became responsible for the current cosm ...

s and other

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pa ...

s 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 greenish (

yellow Yellow is the color between green and orange on the spectrum of light. It is evoked by light with a dominant wavelength of roughly 575585 nm. It is a primary color in subtractive color systems, used in painting or color printing. In th ...

) wavelengths (roughly 540 nm) with ultraviolet are called ''bee purple'' by analogy with

purple Purple is any of a variety of colors with hue between red and blue. In the RGB color model used in computer and television screens, purples are produced by mixing red and blue light. In the RYB color model historically used by painters ...

in human vision.

References

External links

Dalmatian Toadflax
from the Southwest Exotic Plant Information Clearinghouse.
(See archived version on th
Internet Archive
-- accessed on 2009-03-17).
UltravioletPhotography.com
Online library of ultraviolet floral signatures. {{botany-stub Pollination