A look inside those variegated plants
When you go to the greenhouses and garden centers this spring, you will be seeing more and more variegated plants (these are plants with leaves of multiple colors). Variegated plants are becoming more popular because they add interest and contrast, and work well when blending a group of plants. If you have a plant that is green with white variegation, combine it with a plant that is dark green and another plant with white flowers. You will have a striking combination. Likewise, plants that are green with either yellow, or burgundy, or pink variegation can be combined with plants in these related colors.
Plants appear green because of the presence of the green pigment chlorophyll. A white variegation is the result of a plant's inability to produce any pigment in a certain area. Orange, yellow and light green leaf colors result from a lesser production of the green pigment chlorophyll, unmasking the orange carotenoid and yellow xanthophyll pigments and allowing them to appear. Shades of pink, red, and purple are the result of anthocyanin pigments. If produced in sufficient quantities, they can mask even the green chlorophyll pigment. Most deciduous trees and shrubs in our temperate zone produce these colors by these same mechanisms in the fall. Variegation only applies to leaves which hold these colors all season long. The pattern of variegation on a leaf will depend on which cells carry the genetic information for the non-green color.
There are also plants which look like they have a silver color on their leaves. But there are no silver plant pigments. In some cases the "silver" is the result of light reflecting from numerous unpigmented hairs which cover the leaf and give it a furry appearance. The aluminum plant has patches of silver on its leaves because the unpigmented upper layer of the leaf (the epidermis) is lifted from the layer below. Some Colorado Blue spruce appear silver/blue because their needles produce a wax that masks the green color beneath.
Variegation can occur as a result of a virus infection, producing mosaic or streaked symptoms on leaves and/or petals. "Tulipomania," a horticultural craze for tulips with streaked petals, became rampant in the 17th Century in Holland and that craze still continues today.
Some variegation can be unstable, with variegated plants producing all green or all white (albino) shoots or leaves. Wandering Jews, Swedish Ivies, English Ivies, Peperomias and Geraniums are just a few of the varieties which may revert to all green or all albino shoots, regardless of efforts to remove the unwanted colored shoots. All albino plants are doomed since they lack chlorophyll and cannot photosynthesize to make food.
The reduction of chlorophyll in variegated plants results in a lower level of photosynthesis or the process of plant food production. For this reason, variegated plants are generally less robust than their green pigmented counterparts. If they are placed in a shaded location to protect the light color of their leaves, they do not receive enough sunlight to process photosynthesis. If they are placed in bright sunlight, the light areas of their leaves often burn. The best location for most variegated plants is one where they receive morning sunshine and protection from the intense afternoon sun.
Variegation can be a genetic trait or the result of a random mutation. If genetic, the trait can be passed on to offspring via sexual reproduction, although the variegation is not guaranteed. When variegation is a result of mutation, it can be carried forward only via vegetative reproduction, such as division or stem cuttings. If seeds are produced by these plants, the new plant will revert back to one of the parent plants and not look like the variegated plant from which it came. These plants are called hybrids and have special characteristics. They are grown from cuttings. That is why when you go to the greenhouses and garden centers you see more and more beautiful and unusual plants. Proven Winners is one company which develops plants from cuttings. Their plants are more expensive than plants grown from seed. It takes a lot of time and work to develop these different varieties, so they have more cost and effort invested, and we will not likely be able to raise them from seed. However, we love the tantalizing varieties which they develop, and each year they will continue to come out with more and more unusual varieties on which we can spend our money.
Kyle Schulz is a Wadena County Master Gardener from Sebeka, and the regular gardening columnist for the Wadena Pioneer Journal.