The Syringa genus, commonly known as the lilac, is a fragrant deciduous shrub celebrated for its dense clusters of blossoms in the spring. While the name describes a pale purple hue, the flowers are primarily known for shades of lavender and violet. This classic color is what most people associate with the lilac. Extensive cultivation has resulted in a broad spectrum of colors that goes well beyond the expected pastel purple.
The Spectrum of Lilac Hues
Lilacs offer a visual palette extending far beyond the pale shade for which they are named, showcasing a full range of cool and warm tones. Many cultivars produce pure white blooms, such as ‘Mme Lemoine,’ which provides a striking contrast to darker varieties. Other plants display vibrant pink colors, with some varieties offering blossoms that appear nearly magenta or a deep, reddish-purple.
The spectrum also includes hues that lean toward the cooler end, with some varieties exhibiting a color described as true blue, a shade that is difficult to achieve in nature. Cultivars like ‘President Grevy’ are often classified as blue, though the color is a powdery, light wedgwood blue rather than a saturated shade. The common perception of “lilac” color is actually just one point along a continuous gradient of purples, violets, and pinks found in this single genus.
Standard Color Classification
Due to the subtle variations across the more than 1,000 known cultivars, horticulturists rely on a standardized system to accurately categorize lilac colors. This classification system divides all observed lilac colors into seven distinct, internationally recognized groups. These categories move systematically through the spectrum, starting with White and then Pink. The remaining groups cover the core colors of the lilac, including Magenta, Lilac, and Violet. This formal organization helps breeders and enthusiasts identify and communicate the precise color of any given variety.
The seven recognized color groups are:
- White
- Pink
- Magenta
- Lilac (the classic medium-light purple)
- Violet
- Blue
- Purple (representing the deepest shades)
Environmental Influences on Lilac Color
The actual color displayed by a lilac bloom is determined by pigments called anthocyanins, which are water-soluble compounds stored within the flower cells. These pigments are genetically predetermined to produce the flower’s base color, which ranges from red to violet and blue. However, the final shade can be slightly modulated by external factors, primarily the chemistry of the soil.
Anthocyanins are highly sensitive to the acidity or alkalinity of their cellular environment, which is indirectly affected by soil pH. While lilacs, unlike hydrangeas, do not undergo a dramatic color change based on soil pH, the expression of violet and purple tones can shift slightly. Alkaline conditions (higher pH) may cause the color to appear pinker, while acidic conditions (lower pH) can push the color toward the bluer end of the spectrum. Additionally, factors like the intensity of sunlight can influence the perceived color.