Nectar

For other uses of "Nectar", see Nectar (disambiguation).

Nectar is a sugar-rich liquid produced by plants. It is produced in glands called nectaries, either within the flowers, in which it attracts pollinating animals, or by extrafloral nectaries, which provide a nutrient source to animal mutualists, which in turn provide anti-herbivore protection. Common nectar-consuming pollinators include bees, butterflies and moths, hummingbirds and bats.

Nectar is an ecologically important item, the sugar source for honey. It is also useful in agriculture and horticulture because the adult stages of some predatory insects feed on nectar.

Nectar secretion increases as the flower is visited by pollinators. After pollination, the nectar is frequently reabsorbed into the plant.[1]

Contents

Etymology

Nectar is derived from Latin nectar, the favored drink of the gods, which in turn is the Latinized version of Greek νέκταρ, néktar, presumed to be a compound of the PIE roots *nek-, "death", and -*tar, "overcoming", i.e. has a similar etymology to ambrosia, the immortality-conferring food of the gods. The earliest recorded use of its current meaning, "sweet liquid in flowers," is 1609 C.E.[2]

Floral nectaries

Floral nectaries are generally located at the base of the perianth, so that pollinators are made to brush the flower's reproductive structures, the anthers and pistil, while accessing the nectar.

Extrafloral nectaries

Nectar produced outside the flower is generally made to attract predatory insects. These predatory insects will eat both the nectar and any plant-eating insects around, thus functioning as 'bodyguards'.[3] Extrafloral nectaries are generally located on the leaf petioles, mid-rib or leaf margin. They are thought to be modified trichomes and exude nectar from phloem sap. Extrafloral nectaries can be found on species belonging to (amongst others) the genera Salix, Prunus and Gossypium. In many carnivorous plants, nectar serves to attract insect prey.[4]

Natural components of nectar

Although its main ingredient is natural sugar (i.e., sucrose (table sugar), glucose, and fructose),[5] nectar is a brew of many chemicals. For example, the Nicotiana attenuata, a tobacco plant native to the US state of Utah, uses several volatile aromas to attract pollinating birds and moths. The strongest such aroma is benzyl acetone, but the plant also adds bitter nicotine, which is less aromatic and therefore may not be detected by the bird until after taking a drink. Researchers speculate the purpose of this addition is to drive the bird away after only a sip, motivating it to visit other plants to fill its hunger, and therefore maximizing the pollination efficiency gained by the plant for a minimum nectar output.[6] Neurotoxins such as aesculin are present in some nectars such as that of the California Buckeye.[7] All twenty of the normal amino acids found in protein have been identified in various nectars, with alanine, arginine, serine, proline, glycine, isoleucine, threonine, and valine being the most prevalent.[1]

See also

References

  1. ^ a b Nectar - Amino Acids. Robert Thornburg, 04/06/01, Iowa state University. Accessed April 2011.
  2. ^ Douglas Harper. "Online Etymology Dictionary". http://www.etymonline.com/index.php?term=nectar. Retrieved 2007-09-26. 
  3. ^ Plant-Provided Food for Carnivorous Insects - Cambridge University Press
  4. ^ Merbach, M. 2001. Nectaries in Nepenthes. In: C.M. Clarke Nepenthes of Sumatra and Peninsular Malaysia. Natural History Publications (Borneo), Kota Kinabalu.
  5. ^ Nicolson, Susan W.; Nepi, Massimo; Pacini, Ettore (Eds.), "Nectaries and Nectars", Springer Publications, 2007 p.9)
  6. ^ Chemical & Engineering News, Vol. 86 No. 35, 1 Sept. 2008, "Two-Faced Flowers", p. 11
  7. ^ C.Michael Hogan (2008) Aesculus californica, Globaltwitcher.com, ed. N. Stromberg

Bibliography

External links