The presence of a green upper surface and a purple underside on a plant’s leaves is a distinct visual trait common to many popular houseplants and garden specimens. This striking dual coloration is a natural adaptation found primarily in plants that thrive in the shaded environments of tropical forest floors. The difference in color is linked to the plant’s strategy for maximizing light capture and protecting its internal mechanisms from environmental stress.
Common Plants Exhibiting This Dual Coloration
The group of plants exhibiting this green-and-purple pattern is diverse, but several are frequently encountered in cultivation. Many fall under the broad category of “prayer plants” due to their characteristic leaf movement. One of the most common is the Wandering Dude or Inch Plant (genus Tradescantia), particularly Tradescantia zebrina. This plant is recognized by its trailing, vining habit and leaves that display stripes of green and silver on the upper side, contrasting sharply with a solid, deep purple beneath.
Another significant group is the Marantaceae family, which includes the true Prayer Plant (Maranta leuconeura) and the closely related genera Calathea and Stromanthe. Maranta leuconeura varieties, such as the Red-Veined Prayer Plant, feature broad, oval leaves with distinct patterns and vivid red-purple undersides. Many Calathea varieties also possess this trait, such as Calathea roseopicta (‘Rose-Painted Calathea’), which has deep green leaves with decorative markings and a rich burgundy or violet back. These species grow in a bushy, upright clump, unlike the trailing Tradescantia.
Other notable examples include the Purple Waffle Plant (Hemigraphis alternata), which has a quilted, textured green upper surface and a pronounced purple underside, maintaining a compact growth habit. The Purple Velvet Plant (Gynura aurantiaca) is identified by its fleshy leaves covered in soft, velvety purple hairs. Its undersides often show a deeper concentration of the purple pigment against the green. Some cultivars of Rex Begonia (Begonia rex-cultorum), known for their highly patterned foliage, also display a green or silvery top with a red-purple reverse.
The Biological Function of Purple Leaf Undersides
The purple coloration on the underside of these leaves is caused by water-soluble pigments called anthocyanins, which are stored within the cell vacuoles. Anthocyanins absorb light in the blue-green spectrum, causing the leaves to appear purple or red. In plants that grow in low-light environments, such as the tropical forest understory, this pigment placement is an adaptation to improve photosynthetic efficiency.
As light penetrates the green chlorophyll on the upper surface, some photons pass through without being captured. The layer of anthocyanins on the underside acts as a reflective screen, bouncing the transmitted green light back up into the leaf tissue. This mechanism provides a second opportunity for the chloroplasts to capture the light energy, maximizing the plant’s ability to produce energy in shaded conditions.
Anthocyanins also serve a protective role, acting as a form of internal sunscreen. By absorbing high-energy light rays, they shield the photosynthetic machinery from damage caused by excessive light exposure, known as photoinhibition. This protective quality is important when understory plants are exposed to fleeting, intense bursts of sunlight, called sun flecks. Anthocyanins also function as antioxidants, helping to scavenge reactive oxygen species generated during environmental stress.
Caring for and Differentiating the Common Varieties
Distinguishing between the common green-and-purple varieties involves observing their growth structure and leaf characteristics. Tradescantia species are trailing, making them excellent choices for hanging baskets. They are quite resilient, tolerating a wider range of light levels. Their leaves are notably succulent, which helps them survive if the soil occasionally dries out.
In contrast, Calathea and Maranta species (Marantaceae family) are upright and bushy, though Maranta tends to have a more spreading habit. These plants are famous for nyctinasty, the process where their leaves fold upward at night and lower during the day, which is the source of the “prayer plant” common name. They are less tolerant of neglect and are considered more demanding houseplants.
For maintenance, all these species, especially the Marantaceae family, thrive in bright, indirect light, which is necessary to maintain the vibrant purple coloration. Too little light will cause the purple to dull, while direct sunlight can scorch the leaves. Calathea and Maranta require consistently high humidity (ideally 50% or higher) due to their tropical origin. They are sensitive to the chemicals found in tap water, often showing brown leaf tips if not watered with distilled or filtered water. When watering, allow the top inch or two of soil to dry slightly between applications, as consistently saturated soil can lead to root issues.