Chrysanthemums, often called “mums,” are highly cultivated flowering plants renowned for their complex flower heads and late-season blooms. This member of the Asteraceae family displays an extraordinary range of colors due to centuries of breeding. The spectrum of chrysanthemum colors is vast, encompassing nearly every hue imaginable. However, the plant’s natural genetic makeup limits this diversity in one significant area: true blue.
The Spectrum of Natural Colors
The wide array of natural chrysanthemum colors originates from the unique combination and concentration of two primary classes of plant pigments. Warm colors, such as yellows, golds, oranges, and bronzes, are primarily the result of carotenoids. These fat-soluble pigments accumulate in the ray florets of the flower head.
The cool and darker tones rely on water-soluble compounds called anthocyanins. Chrysanthemums naturally produce cyanidin-based anthocyanins, which impart shades of pink, magenta, purplish-red, and deep burgundy. White chrysanthemums occur when both the anthocyanin and carotenoid pathways are shut down, resulting in a petal that lacks color-producing pigment. The interplay between these two pigment groups creates complex variations, such as blending yellow carotenoids and red anthocyanins to form orange or bronze shades.
Colors Not Found Naturally
Despite the extensive palette, chrysanthemums cannot naturally produce a true blue or pure black color. This limitation stems from the absence of a specific enzyme in the plant’s genetic code. The blue color in most flowers is created by a pigment called delphinidin, which requires the enzyme flavonoid 3′,5′-hydroxylase (F3’5’H) for its synthesis.
Chrysanthemums lack the gene that codes for the F3’5’H enzyme, meaning the delphinidin biosynthesis pathway is incomplete. Without this genetic component, the flowers cannot generate the chemical structure required for a blue hue. While deep purple cultivars exist, a true black flower is limited by the plant’s native pigment capacity, requiring an extreme concentration of dark pigments.
Cultivation and Color Modification
Humans have employed various methods to expand the chrysanthemum’s natural color range, primarily through selective breeding and direct alteration. Selective breeding involves cross-pollinating plants with desirable traits to intensify existing hues or create novel shades. This process has resulted in complex bi-colors, unique patterns, and intense, saturated colors like lime green variants or vivid dark reds.
A more direct form of color modification is the common florist technique of artificial dyeing. This method involves submerging the stems of cut white chrysanthemums into water mixed with colored dyes. As the flower draws water up through its vascular system, the dye is absorbed into the petals, creating “novelty” colors like electric blue or rainbow patterns. Genetic engineering has also introduced genes from other plants to create blue-violet shades by inducing delphinidin production, demonstrating the potential for future, permanent color modifications.