What is Variegation?
What is Variegation?
Variegation in plants refers to the appearance of differently coloured zones on the leaves and sometimes on the stems and flowers. These patterns can include patches, stripes, or spots of various colours such as white, yellow, or different shades of green. Variegation is a visually striking characteristic often sought after in ornamental plants for its aesthetic appeal. Variegated cultivars exist in several ornamental genera such as Begonia, Calathea, Hedera, Hosta, Philodendron and Pothos, to name a few.
Causes of Variegation
Variegation can be caused by several factors, including genetic mutations, chimeric tissue, or by viroid/viral infections.
Genetic mutations are the most common cause of variegation. Nuclear mutations affect the DNA within the cell nucleus and can lead to stable, inheritable variegation, often passed down from generation to generation. Plastid mutations, on the other hand, involve changes in the DNA of plastids such as chloroplasts. These mutations can lead to sectors of cells with different colours, and since plastids are inherited maternally in most plants, this type of variegation can also be passed to offspring.
Chimeras represent another source of variegation. A chimera is a plant with two or more genetically distinct types of cells. This can result in sectors of the plant that are genetically different, leading to distinctive patterns of variegation. Chimeras can occur naturally or be induced by mutations or grafting techniques.
Viral infections can also cause damage that appears very similarly to variegation. Certain plant viruses and viroids interfere with the normal production of chlorophyll, leading to manifestation of leaf patterns that appear as mosaic or mottled colours, though this is not considered true variegation.
Types of Variegation
Chimeric variegation arises from mutations or genetic events that create separate distinct cell lineages within a single plant. This can happen naturally or be induced through methods such as grafting. When these genetically different cells proliferate, they form visible patterns of variegation. The variegation remains stable as long as the distinct cell types continue to grow and divide in their respective regions. Chimeric variegation is present in popular Monstera cultivars like Variegata and Albo-Variegata. Chimeral variegation can be stable or unstable, and it is common for plants with this form of variegation to revert back to being entirely green making them harder to propagate whilst reliably maintaining variegation.
Pattern-gene variegation is a type of variegation in plants that results from specific genes dictating distinct colour patterns on the leaves. These genetic patterns can create various designs such as stripes, spots, or patches, often in contrasting colours like white, yellow, or different shades of green. This form of variegation is stable and inheritable, passed down from one generation to the next through the plant's genetic material. Examples of plants with pattern-gene variegation include the Calathea, which displays striking striped leaves, and certain cultivars of Coleus, known for their vibrant, multi-coloured foliage.
Reflective, also known as blistered, variegation is a unique form of variegation in plants caused by air spaces within the leaf tissue that reflect light, giving the leaves a silvery or white appearance. This structural feature, rather than pigment differences, creates the distinctive reflective patterns. The air spaces scatter light, producing a shimmering effect that can vary in intensity and coverage across the leaf surface. Plants like the Watermelon Peperomia (Peremoia argyreia) 'Silver Satin' Pothos (Scindapsus pictus) and some varieties of Begonia are known for their reflective variegation, where the leaves exhibit a silvery sheen or pattern.
Maintenance and Care
Variegated plants often require more specific care compared to their non-variegated counterparts. They typically need more light compared to their green leaved counterparts to compensate for the reduced chlorophyll content in the variegated areas. This ensures that they can still photosynthesize efficiently despite having less green tissue. Propagating variegated plants can also be challenging, as not all methods will retain the variegation. Some variegated plants may revert to solid green when propagated from seed, requiring careful research and selection of propagation techniques to maintain the desired variegated patterns.
Overall, variegation is a fascinating and complex trait in plants, resulting from various biological processes. It adds diversity and aesthetic value to plant collections and landscapes, making variegated plants a popular choice among gardeners and plant enthusiasts.