The question of whether violets are truly violet or actually blue is a common source of confusion. When most people look at the common flower of the Viola genus, its color often appears to be closer to a deep indigo or purplish-blue, leading to the popular rhyme about “violets are blue.” This visual discrepancy highlights a fundamental difference between a scientifically defined wavelength and a historically named pigment. The answer requires separating the physical properties of light from the chemistry of the flower.
Defining Violet in the Visible Spectrum
The color violet is a specific, measurable phenomenon defined by its position in the visible light spectrum. According to physics, violet possesses the shortest wavelength and highest frequency of all visible colors, sitting right at the edge of human perception near ultraviolet light. The wavelengths associated with spectral violet typically fall within the range of approximately 380 to 450 nanometers. When white light passes through a prism, violet is the final color observed before the light becomes undetectable. This pure, spectral violet is a single wavelength of light, distinct from the purple colors we commonly encounter, which are usually mixtures of red and blue light.
The Science Behind the Violet Flower’s Hue
The color of the Viola flower is determined by pigments called anthocyanins, which are water-soluble compounds stored within the plant cells’ vacuoles. Anthocyanins absorb specific wavelengths of light and reflect others, creating the color we perceive. The exact hue produced is highly sensitive to the chemical environment within the flower’s cells, particularly the pH level.
In acidic conditions (low pH), anthocyanins appear red or pink; in neutral or basic conditions (higher pH), they shift toward blue, purple, or indigo. Most common wild violets have a cell sap pH that places their anthocyanins in the purplish-blue to indigo range, differing visually from the pure spectral violet. The final color is often modified by copigmentation, where anthocyanins interact with colorless compounds, or flavonoids, which stabilize the pigment structure and deepen the tones.
The Viola genus is diverse, including hundreds of species that display a variety of colors beyond the namesake, such as white, yellow, and various shades of true purple. However, the most widespread species often exhibit a color visually closer to blue or indigo. This chemical complexity, governed by pH and molecular structure, explains why the flower’s color is not a perfect match for the physical definition of the color violet.
Why the Confusion Exists
The core of the confusion lies in the history of language, as the color was named after the flower, not the spectral color. The word “violet” entered the English language in the late 14th century, derived from the Latin term viola, which referred to the flower itself. At this time, there was no standardized scientific classification of the visible spectrum.
The flower’s purplish-blue shade became the definitive reference point for that specific color range, long before Sir Isaac Newton systematically divided the visible spectrum into seven distinct colors in the 17th century. Newton included violet as one of his seven colors, fitting the new scientific concept into an existing cultural and linguistic framework. The flower’s name thus established the cultural benchmark for the color, even if its biological hue does not precisely align with the modern, technically defined spectral wavelength.
In older forms of English and in common parlance, the terms for colors like blue, purple, and violet were often used with less precision than they are today. The flower’s color occupied the space between blue and purple, and its established name provided a convenient label for that section of the color wheel. This linguistic inertia means the flower remains the namesake for a color whose strict scientific definition it only loosely matches.