April, 2000: Eurasia
Although best known for captivating our feline friends, catnip has many other uses, with new ones still being discovered.
|
|
Nepeta cataria.
Flowers of lamb's ear mint, a typical labiate flower of the Lamiaceae family. Also note the dense covering of hairs on the leaves and other plant organs. (From Stern, Introductory Plant Biology, 8th edition, © 2000 McGraw-Hill Companies, Inc.)
Scientifically known as Nepeta cataria, catnip is a perennial herb native to Eurasia. Although some people consider it a weedy pest, it is now cultivated worldwide as an ornamental. It has also been grown as a medicinal plant and a food source. A hot infusion of catnip can promote sweating and is often used to treat colds, flu, and fevers. Catnip is also said to soothe the nervous system and calm the stomach, aiding both diarrhea and colic. Naturalized in North America, N. cataria has been used as a folk remedy for colds by inhabitants of the southern division of the Appalachian Mountain region since the eighteenth century. It has also been grown for centuries in France where the leaves and shoots have traditionally been used to flavor foods. Most recently, researchers at Iowa State University may have found yet another use for this member of the mint family–as an insect repellent.
N. cataria is in the mint, or Lamiaceae, family. Characteristics of this family of dicots include square-shaped stems and simple leaves lacking stipules. Labiates, another name for the Lamiaceae, are often covered in hairs and glands that emit an aromatic fragrance. The term "labiate" refers to the lip shape typical of the flowers in this family. Additional genera in Lamiaceae include the popular cooking herbs Mentha (mint), Origanum (oregano), Salvia (sage), and Ocimium (basil).
Chemical analysis of the leaf and inflorescence of N. cataria have revealed many volatile oils, acids, tannins, and sterols (steroid alcohol; an example in animals is cholesterol). Specific chemical compounds include thymol, nepetalic acid, valeric acid, nepetalactone, and nerol. The active component in N. cataria responsible for both the euphoric reactions of cats and the repulsion of insects is nepetalactone. Nepetalactone is most concentrated within the leaves and inflorescences between June and September when catnip is coming into flower.
It is not just 80'90% of domesticated cats who find N. cataria irresistible, but also 80'90% of other members of the cat family, including lions, pumas, and leopards. Studies of cat response to N. cataria indicate that their reactions are inherited–either they love it or they ignore it, based on genetic information rather than learned behavior. Research suggests that nepetalactone mimics a pheromone that is found in the urine of male cats and associated with courtship behavior. This may be why cats are so attracted to the herb.
Researchers in the entomology department at Iowa State University have conducted experiments using extracts of N. cataria applied to half a sheet of paper set in a petri dish while the other half remained untreated. German cockroaches were used to test for insect preference for either half of the paper. Overwhelmingly, the roaches chose the untreated side, suggesting that a chemical in the catnip extract was repelling them. Since the roaches showed neither preference nor avoidance for either side when their antennae were removed, this suggests they were specifically avoiding a chemical scent. (Insects have separate sensory structures for tasting and detecting texture, such as sensory palps.) The roaches' reaction may be due to the fact that extracts of catnip have been found, in other research, to mimic juvenile hormone activity. Juvenile hormone inhibits the secretion of ecdysone, which triggers molting (the periodic shedding and secretion of a new exoskeleton). If arthropods are prohibited from molting, their growth is indirectly inhibited as well. Thus, this hormone-mimic may be detected by the roaches (via antennae) and cause them to avoid the catnip-treated portion of the paper when their antennae are intact.
N. cataria has many uses both for and against members of the animal kingdom–as an ornamental, a toy for domesticated cats, a medicinal herb, a food flavoring, and now an insect repellent. Fluffy may have to share the catnip!
References, Websites, and Further Reading
Mabberley, D. J. 1997. The plant-book. 2d ed. New York: Cambridge University Press.
Microsoft Encarta Encyclopedia 99. © 1993–1998 Microsoft Corporation.
Stern, Introductory Plant Biology, 8th Edition
Chapter 6: Stems
Anatomy of a woody twig, p. 85
Chapter 7: Leaves
Internal structure of leaves, p. 108
Illustration of internal leaf anatomy, p. 110
Chapter 8: Flowers, Fruits, and Seeds
Differences between dicots and monocots (including palm growth pattern), p. 129
Chart comparison of dicots and monocots, p. 130
Chapter 11: Growth
Hormones, pp. 188'96
Chapter 23: Flowering Plants
Flower and ovary types, pp. 423–24
Chapter 24: Flowering Plants and Civilization
The Mint Family (Lamiaceae), pp. 448–50
Appendix 2: Biological Controls
Phermones, p. 509
McGraw-Hill Higher Education is one of the many fine businesses of The McGraw-Hill Companies.
If you have a question or a problem about a specific book or product, please fill out our Product Feedback Form.
For further information about this site contact mhhe_webmaster@mcgraw-hill.com
or let us know what you think by filling out our Site Survey.
