Plectranthus scutellarioides

Plectranthus scutellarioides
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Asterids
Order: Lamiales
Family: Lamiaceae
Genus: Plectranthus
Species: P. scutellarioides
Binomial name
Plectranthus scutellarioides
(L.) R.Br.
Synonyms[1]
Plectranthus scutellarioides growing in Pittsburgh, Pennsylvania

Plectranthus scutellarioides (coleus) is a species of flowering plant in the family Lamiaceae, native to south east Asia and Malaysia. Growing to 60–75 cm (24–30 in) tall and wide, it is a bushy, woody-based evergreen perennial, widely grown for its highly decorative variegated leaves.[2] Another common name is painted nettle, reflecting the deadnettle family to which it belongs.

Plectranthus scutellarioides

Names

The name "coleus", still widely used by horticulturalists and gardeners, refers to a defunct genus, and may be regarded as a common name for this species in particular. The name Solenostemon scutellarioides is similarly widely used for this species.

The specific epithet scutellarioides means "resembling the genus Scutellaria", whose name is itself derived from the Latin scutella, meaning a small dish or bowl.[3]

Cultivars

Coleus Inflorescence

Leaves typically show sharp contrast between the colors; the leaves may be several shades of green, pink, yellow, black (a very dark purple), maroon, cream, white and red (somewhat resembling the unrelated Caladium). New cultivars with varieties of colors are constantly being made. The following hybrid cultivars have gained the Royal Horticultural Society's Award of Garden Merit:-

  • 'Crimson Ruffles'[4]      
  • 'Lord Falmouth'[5]
  • 'Picturatus'[6]
  • 'Pineapple Beauty'[7]
  • 'Pineapplette'[8]
  • 'Royal Scot'[9]
  • 'Walter Turner'[10]
  • 'Wisley Tapestry'[11]

Plectranthus scutellarioides color variation is mostly dependent on how much sunlight is available and how intense that light is. Light is the most influential factor in Plectranthus scutellarioides speciation. In plants, green coloration is due to the amount of chlorophyll present in the chloroplasts in the leaves. While Plectranthus scutellarioides foliage does have green pigmentation, the Plectranthus genus is known for its bright reds, purples, pinks, and oranges. These variations in color are due to anthocyanins, water-soluble, flavonoid biosynthetic pigments, found in the foliage in addition to chlorophyll.[12] The increase in anthocyanin production is accompanied by a decrease in chlorophyll production.[12] The production of anthocyanins and chlorophylls are affected by light; the more light is present, the more anthocyanins are produced, with an inverse relationship to the production of chlorophylls. Anthocyanins are created inside the cell in order to facilitate photosynthesis in leaves that are exposed to very intense or prolonged sunlight. Leaves in Plectranthus scutellarioides species that are not exposed to intense or prolonged sunlight have a higher concentration of chlorophylls than anthocyanins[3]. Balance of pigmentation chemicals allows for a wide variety in Plectranthus scutellarioides foliage colors.

The Plectranthus genus is native to many tropical areas in Asia, Australia and Africa.[13] These tropical areas, because of the extreme diversity of flora, have many different niches to fill when it comes to areas of light availability. Plectranthus scutellarioides species can fit almost all of these niches, due to the adaptive radiation the Plectranthus genus underwent, and continues to undergo. Plectranthus scutellarioides plants that grow in areas exposed to extended periods of light tend to display brighter and more variegated leaves. Plectranthus scutellarioides plants that grow in areas near the floor of these tropical forests, and therefore are exposed to less light, often have greener foliage. As time has passed, plants have adapted to the light available in their ecosystems, allowing for greater diversity and speciation of the Plectranthus genus.[14]

Cultivation

The plants grow well in moist well-drained soil, and typically grow 0.5–1 m tall, though some may grow as tall as 2 meters. Coleus are typically grown as ornamental plants. They are heat-tolerant, but they do less well in full sun in subtropical areas than in the shade. In mild areas (no snow in winter), plants can usually be kept as perennials if well managed. In colder areas, they are often grown as annuals, since the plants are not hardy and become leggy with age (to encourage bushing in leggy plants, simply pinch back growing tips). In bright, hot areas, the colors of the plant are typically more intense in shade than in full sun, and the plants will require less water there. Coleus also make low-maintenance houseplants, and can often be propagated by clipping a length of stem just below the leaves and putting the stem in water to root. The plant's flowers grow on a stem above that stem's leaves, and tend to be purple and quite small in comparison to the leaves. The plant is not generally grown for its flowers, as it promotes stem elongation (remove to halt this).

A cultivated variety of coleus

Diseases

One disease that can affect coleus is downy mildew. This mildew appears on the leaves making the plant look dirty because it is brown in color. The organism is called Peronospora sp. and can also result in curled and twisted leaves. Sometimes symptoms are not found on leaves which make the disease harder to control.[15] Another disease is impatiens necrotic spot virus which causes brown or yellow spots on leaves, rings, black or brown stem discoloration, and brown leaf veins, ultimately resulting in plant death. The disease is spread by an insect called a thrips that carries the virus from an infected plant to an uninfected plant. It only takes a few of these insects to infect a whole greenhouse.[16]

Propagation

A cultivated coleus grown as a small tree

There are two ways to propagate Coleus. Seeds are inexpensive and easily obtainable, though desirable named cultivars do not come true from seed. To germinate, simply sprinkle seeds on the surface soil and press down. Seeds need light to germinate, so avoid covering the seeds. To keep seeds moist, grow in a container and cover with plastic, or mist seeds daily (if starting seeds directly in the garden). Sprouts can show color in as little as two weeks. Alternatively, cuttings can be taken. Cuttings root readily in plain water, without the addition of rooting hormone (although it is still beneficial).

Psychoactivity

Coleus blumei (now known as Plectranthus scutellarioides) has been reported to have very mild relaxing and/or hallucinogenic effects when consumed. The effects of the Coleus plant have not been explored very much by modern scientists but the plant has been known to have been used by the Mazatec Indians of southern Mexico who have a history of consuming this plant for its mind-altering effects.[17] It is not known what psychoactive chemical(s) exist in the Coleus blumei plant, as there has been very little research on the subject.[18]

Some people have claimed that they have experienced hallucinogenic effects from chewing several dozen fresh coleus leaves as a quid or brewing them to make a tea, although others have reported feeling no effects at all.[18]

Several authors of internet-hosted trip reports have claimed that smoking dried coleus leaves causes effects similar to smoking dried Salvia divinorum leaves, and the active compounds in the two plants may have similar chemical structures.[19][20] However, some authors claim that only the fresh leaves of the Coleus blumei plant are psychoactive.

Wikimedia Commons has media related to Solenostemon scutellarioides.

References

  1. ↑ "The Plant List: A Working List of All Plant Species". Retrieved June 19, 2014.
  2. ↑ RHS A-Z encyclopedia of garden plants. United Kingdom: Dorling Kindersley. 2008. p. 1136. ISBN 1405332964.
  3. ↑ Hyam, R. & Pankhurst, R.J. (1995). Plants and their names : a concise dictionary. Oxford: Oxford University Press. ISBN 978-0-19-866189-4.
  4. ↑ "RHS Plant Selector - Solenostemon scutellarioides 'Crimson Ruffles'". Retrieved 4 July 2013.
  5. ↑ "RHS Plant Selector - Solenostemon scutellarioides 'Lord Falmouth'". Retrieved 4 July 2013.
  6. ↑ "RHS Plant Selector - Solenostemon scutellarioides 'Picturatus'". Retrieved 4 July 2013.
  7. ↑ "RHS Plant Selector - Solenostemon scutellarioides 'Pineapple Beauty'". Retrieved 4 July 2013.
  8. ↑ "RHS Plant Selector - Solenostemon scutellarioides 'Pineapplette'". Retrieved 4 July 2013.
  9. ↑ "RHS Plant Selector - Solenostemon scutellarioides 'Royal Scot'". Retrieved 4 July 2013.
  10. ↑ "RHS Plant Selector - Solenostemon scutellarioides 'Walter Turner'". Retrieved 4 July 2013.
  11. ↑ "RHS Plant Selector - Solenostemon scutellarioides 'Wisley Tapestry'". Retrieved 4 July 2013.
  12. ↑ 12.0 12.1 Nguyen P. and V. Dal Cin (2009). "The role of light on foliage colour development in coleus (Solenostemon scutellarioides (L.) Codd)". Plant Physiology and Biochemistry 47: 934–945. doi:10.1016/j.plaphy.2009.06.006. PMID 19631554.
  13. ↑ Abraham, M.; Radhakrishnan, V.V. (2004). "Assessment and induction of variability in coleus (Solenostemon rotundifolius)". Indian Journal of Agricultural Sciences 75 (1): 834–6.
  14. ↑ Nguyen, P.; Quesenberry, K.; Clark, D. (2008). "Genetics of Growth Habit and Development of New Coleus (Solenostemon) Varieties with Trailing Habit and Bright Color". Journal of Heredity 99 (6): 573–580. doi:10.1093/jhered/esn054.
  15. ↑
  16. ↑ Plant Disease Diagnostic Clinic University of Wisconsin-Madison and UW-Extension
  17. ↑ Schultes, Richard Evans (1976). Hallucinogenic Plants. Golden Guides. Illustrated by Elmer W. Smith. New York: Golden Press. p. 138. ISBN 978-0-307-24362-1. OCLC 2761333. Retrieved 2011-07-22.
  18. ↑ 18.0 18.1 "Misc Info". Erowid Coleus Vault. Erowid. Retrieved 2011-07-22.
  19. ↑ "Completely Unexpected". Erowid Coleus Vault. Erowid. Retrieved 2011-08-08.
  20. ↑ "Definitely Not Placebo". Erowid Coleus Vault. Erowid. Retrieved 2011-08-08.