The appearance of rich red and deep black coloration in plants offers a striking visual contrast, making these varieties highly sought after in modern gardening and landscaping. These dark hues introduce depth and drama to a space, often appearing almost black when viewed in certain light conditions. While the color is commonly referred to as black, it is typically a very concentrated shade of deep maroon, purple, or burgundy. These visually intense plants create dramatic focal points and provide a sophisticated backdrop for brighter greens and vivid blooms.
The Science Behind Red and Black Pigmentation
The rich red and near-black colors in plants are primarily caused by the accumulation of pigments known as anthocyanins. These water-soluble compounds are responsible for nearly all the red, purple, and blue hues found in plant tissues, residing within the cell vacuoles. The perception of a plant as “black” occurs when there is an extremely high concentration of these pigments, specifically cyanidin-based anthocyanins, which absorb nearly all light wavelengths. This intense pigmentation effectively masks the green color of chlorophyll, resulting in the deep, dark appearance of the foliage or flower.
The production of anthocyanins serves several biological purposes beyond aesthetics. A primary function is to act as a protective compound, absorbing harmful ultraviolet (UV) radiation and shielding the underlying photosynthetic machinery. The development of dark coloration is often a response to environmental stress, functioning as an antioxidant to help the plant tolerate conditions like cold, drought, or excessive light. The pigments can also play a role in attracting specific seed dispersers or deterring herbivores.
Identifying Common Red and Black Plants
Many popular garden varieties have been selectively bred to exhibit this intense coloration in their foliage or flowers.
Ornamental Foliage
Among ornamental foliage plants, the succulent Aeonium arboreum ‘Zwartkop’ (Black Rose) is known for its large, spoon-shaped rosettes that darken to a rich purple-black in full sun. Heuchera cultivars like ‘Black Pearl’ feature ruffled, nearly-black leaves that provide ground cover and contrast against other perennials. Another striking example is Ophiopogon planiscapus ‘Niger’, commonly known as Black Mondo Grass, which forms dense clumps of slender, nearly jet-black foliage.
Flowering Plants
In the realm of flowering plants, the deep coloration often provides a stunning contrast to the flowers themselves. Certain varieties of Crape Myrtle (Lagerstroemia), such as ‘Center Stage Red’, are prized for their nearly black foliage that highlights their cherry-colored blooms. The Chocolate Cosmos (Cosmos atrosanguineus) is famous for its velvety, dark maroon petals that appear black and emit a vanilla-like scent. For annual plantings, Coleus scutellarioides ‘Black Prince’ offers broad, dark leaves that maintain their moodiness even when grown in partial shade.
Edible Varieties
Dark coloration is also seen in specific vegetable and fruit varieties. Ornamental peppers, such as ‘Black Pearl’ or ‘Black Prince’, develop foliage that is a deep, purplish-black, providing a dramatic backdrop for their bright red or purple fruit. The dark purple-black hue found in certain varieties of rice, corn, and carrots is also due to the high concentration of cyanidin-based anthocyanins. These food crops demonstrate that the same pigment mechanism responsible for ornamental color is also present in edible species.
Environmental Factors Affecting Color Intensity
The depth and saturation of the red and black color are highly dependent on the plant’s environment, as pigment production is often a protective response. High light exposure is the most significant factor, as intense sunlight triggers the plant to produce more anthocyanins to shield its photosynthetic cells from UV damage. For many dark-leaved varieties, moving the plant from a shady location to one with maximum sun exposure will noticeably intensify the color, darkening purple or burgundy leaves to a richer, near-black shade.
Temperature and other forms of environmental stress also play a role in color development. Cooler temperatures or slight nutrient deficiencies, such as a lack of phosphorus, can induce a stress response that leads to increased anthocyanin synthesis. However, these factors must be managed carefully, as excessive heat or prolonged high temperatures can accelerate the degradation of anthocyanin molecules, causing the color to fade or brown.
The acidity of the plant’s cellular environment, or pH, influences the exact shade of the anthocyanin pigment. While the pH of the soil has a less direct impact on the foliage color of most plants, the internal pH of the cell vacuole determines whether the pigment presents as more red (acidic) or more blue (alkaline). Maintaining stable, slightly acidic conditions can help ensure the pigments lean toward the deep red and purple spectrum, maximizing the near-black effect.