Aloe vera

Of the more than 300 species of aloe, the most popular medicinal variety is currently Aloe vera. The nomenclature of Aloe vera has been somewhat confused, as the plant has been known by a variety of names, most notable Aloe barbadensis and Aloe vulgari. Historical records indicate that the medicinal use of aloe may have started in Egypt or the Middle East. Since then aloe has been introduced and naturalized throughout most of the tropics and warmer regions of the world, including the Caribbean, the southern United States, Mexico, Latin America, the Middle East, India, and other parts of Asia. Aloe vera is a perennial plant with yellow flowers and tough, fleshy, triangular or spear like leaves arising in a rosette configuration. The leaves are up to 20 inches long and 5 inches across at the base, tapering to a point. There may be as many as 30 leaves per plant. The margins of the leaf are characterized by saw like teeth. Inside, the meaty, leaf is filled with gel that arises from a clear, central, mucilaginous pulp. A mature aloe measures 1 ½ to 4 feet high, with a base 3 feet or more in diameter. The leaf is composed of three distinct layers: an outer layer of tough tissue; a corrugated lining just beneath the outer layer; and the major portion of the leaf, the inner layer consisting of parenchymal cells containing large vacuoles of a semisolid, gelatinous transparent gel. The bitter latex of the corrugated layer protects the plants from predators. Should an animal bite the leaf, the sap causes irritation. The dried latex (juice) derived from the corrugated layer is the source of the laxative properties of aloe. The parenchymal tissue, or gel, is the portion of the aloe used in other applications.