Oleander (Nerium oleander) is a versatile and resilient evergreen shrub renowned for its prolific and vibrant blooms. From a botanical perspective, the array of colors is a result of selective cultivation and hybridization, which has expanded the natural variation found in wild populations. The plant's flowering morphology is characterized by large terminal clusters (cymes) of funnel-shaped flowers, each with five spreading corolla lobes. The available colors span a wide spectrum, primarily manifesting in the petals, though some cultivars feature throat spotting or variegation for added complexity.
The most fundamental and commonly encountered oleander bloom colors are shades of pink, red, and white. The classic, wild-type oleander typically presents in a soft to medium pink. Through cultivation, the pink palette has been vastly extended to include everything from very pale, almost blush tones to deep, vibrant magentas and salmons. The red varieties are equally diverse, ranging from bright, true scarlet and crimson to deeper, somber burgundy and wine-colored hues. Pure white oleanders are also extremely popular, offering a stark, clean contrast against the plant's deep green, leathery foliage and providing a brilliant luminosity in garden settings, especially at dusk.
A significant development in oleander breeding has been the introduction of yellow and apricot-colored blooms. These varieties are often the result of complex hybridization and are generally less common than the pinks, reds, and whites. The yellow coloration can vary from a pale, creamy buttercup to a more vivid, sunny yellow. Apricot varieties blend soft orange, peach, and pinkish tones, creating a warm and unique floral display. The achievement of stable yellow pigmentation in oleanders is a notable horticultural accomplishment, as these pigments (carotenoids) are not as dominant in the species' natural genetic makeup as the anthocyanins that produce pink and red.
Beyond solid colors, many oleander cultivars exhibit striking variegation and multi-colored patterns. This is most frequently expressed as a different colored throat or center within the bloom. A common example is a white flower with a contrasting red or yellow star pattern radiating from the center, or a pink flower with a deep maroon throat. These patterns are caused by differential pigment expression within the cells of the corolla. Some cultivars even feature flowers with petals edged (picoteed) in a contrasting color, or blooms that display a gradient effect, fading from one hue to another. This adds a layer of intricate beauty to the floral structure.
While not a color in itself, the flower form—single or double—dramatically influences the visual impact of the bloom's color. Single flowers have one whorl of five petals and a prominent central pistil and stamen cluster. This form often presents the color in a more open, classic shape. Double flowers, however, possess multiple layers of petals (petaloids), resulting in a fuller, rose-like appearance. The density of the double form can make colors appear more intense and saturated, as there is a greater surface area of pigmented tissue. A deep red double flower, for instance, will often look richer and more voluptuous than its single-flowered counterpart.
