The genus Delphinium, commonly known as Larkspur, features flowering plants instantly recognizable by their stately, vertical spikes of blossoms. Native to the Northern Hemisphere, these plants are defined by the intense color of their flowers. While the species exhibits a surprising range of hues from white to red, the genus is overwhelmingly known for producing some of the most saturated and true blue colors found in the plant kingdom.
The Dominant Color Palette
The most characteristic shades of the Delphinium flower are found within the blue and purple spectrum. These colors range from light, ethereal sky blue to deep, almost inky sapphire shades. Many cultivars exhibit rich violet, lavender, and royal purple hues, which are often mixed with blues on the same flower spike.
A notable feature within the blossom is the contrasting cluster of small, true petals, often referred to as the “bee.” This central eye frequently appears in stark white, black, or a pale contrasting blue, providing an additional layer of color complexity. For instance, the ‘Black Knight’ cultivar displays dark blue flowers with a distinctive black bee, while ‘Guinevere’ features a lavender-pink bloom with a white center. This color contrast highlights the saturated tones of the surrounding large, petal-like structures.
The Spectrum of Cultivated Varieties
While the blues and purples dominate the natural species, selective breeding has expanded the Delphinium color range considerably for horticulture. Modern hybrids offer a full spectrum that includes pure white and soft cream varieties, which provide an elegant contrast to the darker hues. Pink tones, from delicate blush to deeper rose and magenta, are also available through cultivated varieties. These pinks are achieved by shifting the balance of pigments away from the blue-producing compounds.
Specialized breeding has introduced colors into the genus, particularly through crosses involving species like Delphinium nudicaule. These efforts have resulted in cultivars that display scarlet, reddish, and occasionally yellowish or orange tints, which are highly unusual for the genus. Hybrid groups, such as the New Millennium series, focus on creating stronger plants that reliably offer this expanded color palette, including unique bi-colored and multi-shaded blooms.
Understanding the Unique Color Intensity
The remarkably vivid coloration in Delphinium flowers is a direct result of specialized chemical compounds known as anthocyanins, which are water-soluble pigments. The specific anthocyanin responsible for the blue and purple shades is delphinidin, a compound that naturally produces a blue color. The precise hue is regulated by the concentration of delphinidin and the acidity, or pH level, within the flower’s vacuole. A more alkaline environment promotes a shift toward truer blues, while an acidic environment favors red or pink tones.
The intensity and stability of the blue color are further enhanced by a process called copigmentation and chelation. In Delphinium, the delphinidin pigment is often modified by the attachment of sugar and organic acid molecules, creating complex structures known as polyacylated anthocyanins. These large molecules stabilize the blue pigment against environmental changes. They can also form complexes with metal ions, such as Aluminum or Magnesium, within the cell. This metallic chelation provides an additional stabilizing effect, resulting in the brilliant, non-fading blues characteristic of the Delphinium.