Variegation in plants refers to the appearance of multiple colors on leaves, stems, or flowers, rather than a uniform green. This phenomenon can occur naturally and is often a result of genetic changes within the plant. While some variegation patterns are stable and consistent, others emerge spontaneously and can be quite unpredictable.
Understanding Sport Variegation
Sport variegation specifically describes a distinct color or pattern change that arises from a spontaneous genetic mutation within the somatic (non-reproductive) cells of a plant. This mutation often results in a sectorial change, appearing as an unexpected splash, stripe, or blotch of a different color on a leaf, stem, or even a flower. For instance, a solid green plant might suddenly produce a branch with white or yellow sections.
This change is caused by an alteration in the plant’s chloroplast genes, which affects chlorophyll production and distribution. Since chlorophyll is responsible for green pigmentation, a mutation can lead to areas with reduced or absent green color.
The mutation typically impacts only a portion of the plant, creating a genetic mosaic where the “sport” exhibits new characteristics while the “mother plant” retains its original appearance.
Because the genetic change occurs in somatic cells, it is not passed on through seeds. Therefore, plants grown from seeds of a sport variegated plant will typically revert to the original, non-variegated form of the parent.
Sport Variegation Compared to Other Types
Sport variegation is one of several ways plants can display multi-colored foliage, and it stands apart from other types.
Chimeral variegation involves different tissue layers within the plant having distinct genetic compositions. This results in defined patterns, such as sections of white, cream, or yellow, due to some cells lacking chlorophyll.
In contrast, genetic or inherent variegation is stable and consistently passed down through generations via seeds, as the variegation is coded directly into the plant’s DNA. Plants with inherent variegation, like many prayer plants (Calathea family), exhibit predictable and often symmetrical patterns on every leaf.
Viral variegation, another distinct type, is caused by plant viruses that induce patterns of discoloration on leaves. Unlike sport variegation, viral variegation can spread throughout the plant and may or may not affect plant vigor.
Stability and Reversion in Sport Variegation
Sport variegation, originating from spontaneous somatic mutations, can be inherently unstable. This instability often leads to a phenomenon known as “reversion,” where the variegated portion of the plant begins to produce all-green foliage, returning to its original, non-variegated form.
Reversion occurs because the green, non-mutated cells often grow more vigorously and efficiently than the variegated cells, which have less chlorophyll and thus reduced photosynthetic capacity.
Environmental factors can sometimes influence reversion. Stressors such as insufficient light, extreme temperatures, or improper watering can encourage a plant to revert, as producing more chlorophyll-rich green tissue is a survival mechanism.
To manage reversion, promptly prune any all-green shoots as soon as they appear. This practice helps direct the plant’s energy towards maintaining the desirable variegated growth and prevents the more vigorous green sections from dominating the plant.
Propagating Sport Variegated Plants
Successfully propagating sport variegated plants requires specific methods due to the nature of their mutation.
Since the variegation originates from a somatic genetic change, seed propagation is generally ineffective for maintaining the variegated trait, as offspring are likely to be entirely green.
To preserve sport variegation, vegetative propagation methods are necessary. Taking stem cuttings, performing divisions, or using tissue culture are effective strategies.
When taking cuttings, select sections that clearly display the desired variegation, ideally with a mix of both variegated and green tissue to ensure sufficient photosynthetic capability for the new plant. Nodes on the stem that exhibit variegation are particularly important, as these are the points from which new variegated growth is most likely to emerge.