The Prickly Pear Cactus

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November, 2000: Mexico

 

Baskets of Opuntia sold in Milpalta, a Mexican marketplace. The women are preparing the cladophylls for sale by removing the spines with knives. (Photo courtesy of Gabriela Ocampo.)

Opuntia food products on the market include cladophyll diced and preserved in brine and marmalade made from the "tuna," or Opuntia fruit. (Photo courtesy of Gabriela Ocampo.)

Opuntia cosmetic products on the market include shampoo, face cream, hand and body lotion, and hair gel. (Photo courtesy of Gabriela Ocampo.)

 

The prickly pear cactus, Opuntia, has traditionally been an important part of Mexican culture. The plant itself, called "nopal" by the locals, has been the source of legends, magic, and rituals. The fruits and flattened stems are still used locally for food and medicine, but now Opuntia and its products are receiving increased attention outside their native region as the value of this hardy xerophyte is recognized.

Opuntia is one of about 87 genera in the Cactaceae family, whose distribution includes North, Central, and South America. Opuntia is a succulent plant with tissue specialized for water storage. Small, well-defined regions on the plant surface called areoles are considered specialized lateral branches. Spines covering the plant surface are modified leaves that reduce water loss, conduct water, and protect the succulent tissue from herbivores and other predators. The spines arise from the areoles and are often surrounded by short, barbed hairs called glochids.

Because the leaves are reduced to spines, photosynthesis is undertaken by young green shoots before they mature and become corky and by the flattened modified stems called cladophylls. The shallow roots are adapted for water absorption near the soil surface. The flowers of Opuntia are sessile, bisexual, and solitary. The fruit is an edible berry that can detach, grow roots and shoots, and form a new plant.

The fruit of Opuntia, also known as the "tuna" in Mexican culture, can be eaten fresh, made into jam, syrup, or marmalade, or used as a deep-red dye. A Mexican beverage known as "horchata," made with ground rice, almonds, milk, and the pulp of the Opuntia fruit, has gained popularity through the daily television program "Martha Stewart Living." The cladophylls are also edible and sold, with their spines removed, in marketplaces. The cladophylls can be boiled for several minutes, cut into smaller pieces, and then eaten as a salad or vegetable side dish. They have also been preserved in brine to make them available for sale to a wider market. The pulp of the cladophylls has been used as an ingredient in face and body lotions, hair gels, and shampoo.

Phytochemical investigation of Opuntia reveals 17 amino acids, eight of which are essential. Studies are being conducted to substantiate the medicinal value of the nopal. Research has shown that Opuntia can stabilize blood sugar levels and is especially effective against type II diabetes. It is also used in the fight against high cholesterol and the battle of the bulge. Apparently nopal prevents excess blood sugar from converting into fats and has an LDL-lowering effect. (LDL, low-density lipoprotein, is the "bad" cholesterol and the one to keep low, while HDL, high-density lipoprotein, is the "good" cholesterol.)

Nopal is full of vitamins and minerals, such as the B vitamins, calcium, magnesium, iron, and fiber. Because of the high content of insoluble fiber (cellulose and lignin), many people use Opuntia products to aid digestion and monitor regularity.

You may associate Opuntia with its introduction and aggressive spread throughout Australia where it quickly out-competed and overgrew other native plant species. Since no native predators existed to put this growth in check, biological controls eventually had to be implemented. Cactoblastus cactorum, a moth and natural Opuntia predator, was deliberately introduced into Australia to control the Opuntia population, a method known as "integrated pest management." Introduction of alien species is always risky, but perhaps if the benefits of Opuntia had been realized in the 1920s, the plants could have been harvested instead of being destroyed by C. cactorum.

Although much research still needs to be done, Opuntia has tremendous commercial potential for foods, cosmetics, and medicines. The prickly pear cactus has come a long way from being considered a pest.

References, Websites, and Further Reading

Harris, J. G., and M.W. Harris. 1994. Plant identification terminology: An illustrated glossary. Spring Lake Publishing.

Heywood, V.H. 1993. Flowering plants of the world. New York: Oxford University Press, pp. 63—65.

Simpson, B.B., and M.C. Ogorzaly. 1995. Economic botany: Plants in our world. 2d ed. New York: McGraw-Hill Publishing Company, pp. 672—75.

Velazquez, E. 1998. El nopal y su historia. Mexico City: Clio Publishing Company, p. 35.

http://www.nopal.com/ Nopal website

http://www.ftg.org/research/Semaphorecactus.html Fairchild Tropical Garden, Opuntia corallicola

http://www.cactus-mall.com/index.html#orgs Cactus and Succulent Plant Homepages

http://encarta.msn.com "Cactus," Microsoft® Encarta® Online Encyclopedia 2000. © 1997—2000 Microsoft Corporation.

http://encarta.msn.com/find/Concise.asp?z=1&pg=2&ti=761554303&cid=2#p2 Luther Burbank and his work as a horticulturist and botanist

Stern, Introductory Plant Biology, 8th Edition

Chapter 2: The Nature of Life
Cellulose, p. 23
Proteins and amino acids, pp. 24—25

Chapter 3: Cells
The cell wall (lignin and cellulose), pp. 33—36

Chapter 6: Stems
Types of specialized stems, fig. 6.14, p. 96
Cladophylls, p. 97 and fig. 6.15

Chapter 7: Leaves
Spines, thorns, and prickles, p. 115

Chapter 8: Flowers, Fruits, and Seeds
Structure of flowers, pp. 129—32
Kinds of fruits, pp. 132—33

Chapter 10: Plant Metabolism
Photosynthesis, pp. 166—78

Chapter 15: Evolution
Evidence for evolution and adaptations, pp. 258—59

Chapter 24: Flowering Plants and Civilization
Cactaceae, pp. 447—48 and fig. 24.15A

Chapter 25: Ecology
Xerophytes, p. 464

Chapter 26: Biomes
Desert, pp. 485—86

Appendix 2: Biological Controls
pp. 507—9

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