The vibrant colors of flowers are a sophisticated form of communication designed to attract pollinators like bees. This symbiotic relationship is fundamental to plant reproduction, as the flower provides nectar and pollen in exchange for the transfer of genetic material. A bee perceives a flower’s hue drastically differently than a human, making color a primary, yet complex, visual signal in the search for sustenance.
Bee Vision and Color Perception
Bees possess a visual system that differs significantly from human sight, shaping their color preference. Like humans, bees have trichromatic vision, but their receptors are sensitive to ultraviolet (UV) light, blue, and green wavelengths, unlike the human combination of red, green, and blue. This means they can perceive colors like blue-green and violet, but they cannot register red.
The ability to see UV light gives bees an advantage when foraging, allowing them to detect wavelengths invisible to the human eye. A flower that appears uniformly white or yellow to a person often displays complex patterns in the UV spectrum to a bee. This specialized vision allows bees to quickly differentiate flowers and process color changes, making them highly efficient at finding food sources.
The Preferred Color Palette
The colors most attractive to bees are a direct result of their unique visual system. Bees are highly drawn to colors in the shorter-wavelength end of the spectrum, principally violet, blue, and purple. These colors are vibrant to the bee’s eye because they strongly stimulate the blue and UV photoreceptors.
Yellow and white flowers are also attractive, often reflecting the UV light that bees perceive. Bees can also see “bee’s purple,” a mixture of yellow and ultraviolet light invisible to humans. Conversely, true red flowers are ignored by bees; lacking a red photoreceptor, the flower appears black or gray, offering little contrast against green foliage.
Hidden Signals in Flowers
A flower’s perceived color is only part of the message it sends to a bee; navigational aids are often hidden in the UV spectrum. Many flowers feature patterns known as nectar guides, which absorb or reflect UV light differently than the rest of the petal. To a human, the petal may be a solid color, but to a bee, these guides appear as distinct lines, dots, or a central “bulls-eye” pattern.
These contrasting patterns function like a runway, directing the bee straight to the flower’s center where nectar and pollen are located. The visual contrast reduces the time a bee spends handling the flower, increasing foraging efficiency and the plant’s chance of pollination. This strategy ensures the bee is rewarded quickly and guided accurately to the reproductive parts of the plant.
Practical Planting Choices
Gardeners should select flowers that maximize the visual signals bees are primed to detect. Prioritize plants with blooms in shades of purple, blue, and violet, such as lavender, asters, borage, and salvia, which are universally appealing. Yellow flowers like cosmos and calendula also serve as strong visual beacons.
When choosing varieties, select single-petal flowers rather than highly cultivated double-petal varieties. Double flowers have been bred to replace stamens with extra layers of petals, often concealing the nectar and pollen. This makes it physically difficult for the bee to reach the reward. Simple, open blooms ensure easy access to resources.