Aloe, also written Aloë, is a genus containing about four hundred species of flowering succulent plants.

The APG II system (2003) placed the genus in the family Asphodelaceae. In the past it has also been assigned to families Aloaceae and Liliaceae. Members of the closely allied genera Gasteria, Haworthia and Kniphofia which have a similar mode of growth, are also popularly known as aloes. Note that the plant sometimes called "American aloe" (Agave americana), belongs to Agavaceae, a different family.

Most Aloes have a rosette of large, thick, fleshy leaves. The leaves are often lance-shaped with a sharp apex and a spiny margin. Aloe flowers are tubular, frequently yellow, orange or red and are borne on densely clustered, simple or branched leafless stems.

Many species of Aloe are seemingly stemless, with the rosette growing directly at ground level; other varieties may have a branched or un-branched stem from which the fleshy leaves spring. They vary in colour from grey to bright green and are sometimes striped or mottled.

Uses

Aloe species are frequently cultivated as ornamental plants both in gardens and in pots. Many Aloe species are highly decorative and are valued by collectors of succulents. Some species, in particular Aloe vera are purported to have medicinal properties.

Other use of Aloes include their role in alternative medicines (see Herbalism) and in home first aid. Both the translucent inner pulp as well as the resinous yellow exudate from wounding the Aloe plant is used externally to relieve skin discomforts and internally as a laxative. To date, some research has shown that Aloes produce positive medicinal benefits for healing damaged skin. Conversely, other research suggests Aloe vera can negatively effect healing (Vogler and Ernst, 1999).

Some Aloe species have also been used for human consumption. For example, drinks made from or containing chunks of aloe pulp are popular in Asia as commercial beverages and as a tea additive; this is notably true in Korea.

External uses

Various extracts of Aloe vera are frequently used in herbal medicine and by cosmetic companies. For more information see: Aloe vera.

Internal uses

Aloe contains a number of medicinal substances used as a purgative. The medicinal substance is produced from various species of aloe, such as A. vera, A. vulgaris, A. socotrina, A. chinensis, and A. perryi. Several kinds of aloes are commercially available: Barbadoes, Socotrine, Hepatic, Indian, and Cape aloes. Barbadoes and Socotrine are the varieties most commonly used for curative purposes.

Aloes is the expressed juice of the leaves of the plant. When the leaves are cut, the juice that flows out is collected and evaporated. After the juice has been removed, the leaves are sometimes boiled to yield an inferior kind of aloes. The juice of the leaves of certain species, e.g. Aloe venenosa, is poisonous.

There have been very few properly conducted studies about possible benefits of aloe gel taken internally. One study found improved wound healing in mice. Another found a positive effect of lowering risk factors in patients with heart disease. Some research has shown decreasing fasting blood sugar in diabetic animals given aloe [1]. None of these studies can be considered to be definitive, and there are many false advertising claims for aloe.

Aloe has been marketed as a remedy for coughs, wounds, ulcers, gastritis, diabetes, cancer, headaches, arthritis, immune-system deficiencies, and many other conditions when taken internally. However, these uses are unsubstantiated; the only substantiated internal use is as a laxative. Furthermore, there is evidence of significant adverse side effects (see for example this paper). Genotoxicity studies show that aloe-containing laxatives pose cancer risk to humans when used as directed[2]. Consult your doctor when contemplating taking Aloe internally. Avoid use during pregnancy because the anthraquinone glycosides are strongly purgative. High doses of the leaves can cause vomiting.

On 9 May 2002, the U.S. Food and Drug Administration issued a final rule banning the use of aloe and cascara sagrada as laxative ingredients in over-the-counter drug products[3].

Heraldry

The aloe plant occurs as a charge in heraldry.

Species

There are around 400 species in the genus Aloe. For a full list, see List of species of genus Aloe. Species include: