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Confocal Microscopy Image Gallery
Plant Tissue Autofluorescence Gallery
Coleus Stem
Approximately 150 species of plants belong to the genus Coleus, which is classified as part of the mint family, Lamiaceae. Many of the species, which are also commonly known simply as coleus, display brightly colored foliage that makes them popular as ornamentals.
Coleus was especially fashionable with the Victorians, but fell out of favor during most of the twentieth century. This change may have been partly due to an increasing number of commercial growers opting to produce the plants from seed rather than cuttings in an attempt to cut labor and cost. Seed-grown specimens tend to flower more vigorously than those grown from cuttings, and although flowering is desirable for many ornamentals, this is not the case for coleus. The flowers of coleus plants, which typically grow in spikes during late summer, are small and unattractive in comparison to their leaves. Also, if the plants are allowed to flower and seed, foliage growth declines and sometimes ceases completely.
Most cultivated species of coleus are native to Southeast Asia, Malaysia, and Java. The plants are heat-tolerant, but traditional strains of coleus thrive best in shaded areas. A revival of interest in the plants in the late 1990s, however, was marked by the introduction of a number of sun-loving, magnificently colored varieties. The plants are now available in a tremendous array of hues and patterns and are suitable for a significantly wider range of environments than before. The plants can be maintained perennially under optimal conditions, but because even the slightest frost will kill them and their appearance often becomes less attractive with age, they are frequently sold as annuals.
Contributing Authors
Nathan S. Claxton, Shannon H. Neaves, and Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.