The term, "variegated" is applied to a flower or, more often, a leaf that has more than one color. Most often, it will be two-toned (that is, bi-colored). Often this will mean the foliage is blotched, striped, or bordered with a lighter color than that on the rest of it (or vice versa). The term is also applied more broadly to a whole plant that bears such leaves or blossoms. The corresponding noun for this definition is "variegation."
Different Types of Variegation
Variegated foliage is less commonly tricolored (or even quadricolored, as in the case of the aptly named Agave lophantha 'Quadricolor,' which bears four colors on one leaf). Examples of plants that bear leaves containing three colors are Harriet Waldman' Japanese maple tree (Acer palmatum), Arctic kiwi vine (Actinidia kolomikta 'Arctic Beauty), 'Tricolor' sage (Salvia officinalis), and the Tricolor beech tree (Fagus sylvatica 'Roseomarginata').
Another interesting twist in the tale of variegation is that the two colors found on a plant's leaves can change according to the season. Thus Lysimachia punctata 'Alexander' is a variegated plant, but, whereas the two different colors in early spring are pink and green, in the summer they are white and green.
Indeed, a plant with variegated foliage may have much greater display value at one time of the growing season than at another. Take Golden Shadows pagoda dogwood (Cornus alternifolia 'Wstackman'), for instance: Its leaves have at least two colors in them throughout the growing season, but they look their best in spring and in fall, when they take on the third color. Another dogwood, Cornus kousa 'Wolf Eyes,' looks best in summer, when its flowers keep its bicolored leaves company.
If you like the idea of having variegated plants in your landscaping, one plant that you may come to adore is 'Nora Leigh,' a type of phlox. This novelty bears not only two-toned leaves but also two-toned flowers.
What Causes Variegation and Why Plants Lose It
What is the reason behind the variegation? How do these odd-balls of the plant kingdom form, in the first place? Well, there is more than one possible cause. But as the Royal Horticultural Society remarks, the variegated plants you see for sale on the shelves of garden centers are generally the result of mutations that plant developers have found and propagated.
When a branch or stem on a variegated plant starts to lose one of its colors and its leaves turn all green, it is said to be "reverting." Since a variegated plant is a mutation (a freak, if you will), it is simply returning to a more natural state when it reverts. You can forestall such reverting by faithfully pruning branches whose leaves are turning all green, as soon as you spot them. Do not allow such branches to take over the plant.
Other Examples of Variegated Plants
A number of shrubs bear variegated foliage. There are three examples in the Euonymus genus that are commonly grown in people's landscaping: 'Emerald Gaiety' euonymus, Moonshadow' euonymus, and Emerald 'n' Gold euonymus.
Other commonly-grown bushes that have leaves with more than one color include the variegated red-twig dogwood (Cornus alba 'Elegantissima'), Weigela florida 'Variegata', 'Sugar Tip' rose of Sharon (Hibiscus syriacus), and Daphne x burkwoodii 'Carol Mackie.'
But other types of plants can bear two-toned leaves, too; for example (in addition to the vine, shrubs, and trees already mentioned): Several popular hosta ground covers for shade, such as 'Francee,' 'Frances Williams,' 'Minute Man,' and 'Patriot' hosta. Petasites hybridus 'Variegatus,' a bicolored butterbur, bears two-twoned leaves. Even some annuals get in on the fun, such as the 'Dancing Flame' cultivar of red salvia. There is also the Dalmatian iris (Iris pallida 'Aureo-Variegata'), A kind of columbine known as Aquilegia vulgaris 'Woodside Variegata,' and the Joseph's coat plant (Alternanthera), tropical treated as an annual up North.
Various kinds of ornamental grasses and grass-like plants have variegated leaves, too. This includes the Carex 'Spark Plug', which is a kind of sedge, Zebra grass (Miscanthus sinensis 'Zebrinus'), Golden Hakone grass (Hakonechloa macra 'Aureola'), and 'Silver Dragon' border grass (Liriope spicata).
Even though a plant may be pretty due to its being bicolored, that does not mean that you should necessarily grow it. Some variegated plants have drawbacks that cancel out their beauty. Yellow archangel (Lamiastrum galeobdolon), for example, is an invasive plant. Ribbon grass (Phalaris arundinacea) is also too aggressive to grow in most yards.
Plants bearing variegated leaves are quite popular in landscaping, partly because the display given by their attractive leaves usually lasts longer than the color provided by flowers. If you want continuous color in the garden, it is much easier to get it with pretty leaves than by trying to achieve just the right sequence of bloom with your flowers.