Aloe.
Aloe succotrina
Scientific classification
Kingdom: Plantae (unranked): Angiosperms (unranked): Monocots Order: Asparagales Family: Asphodelaceae Genus: Aloe L.
Species
See Species

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

The genus is native to Africa, and is common in South Africa's Cape Province, the mountains of tropical Africa, and neighbouring areas such as Madagascar, the Arabian peninsula, and the islands off Africa.

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 Aloe species 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, pink or red and are borne on densely clustered, simple or branched leafless stems.

Many species of Aloe appear to be stemless, with the rosette growing directly at ground level; other varieties may have a branched or unbranched stem from which the fleshy leaves spring. They vary in colour from grey to bright-green and are sometimes striped or mottled. Some Aloes native to South Africa are arborescent. ^[1]

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. It is claimed to have some medicinal effects, which have been supported by scientific and medical research - see references on article on Aloe vera.

Historical uses

Historical use of various Aloe species by humans is well documented, though the species of Aloe used and their clinical effectiveness remain unknown.^[2]

Of the 300 species of Aloe, only a few were used traditionally as a herbal medicine. This includes Aloe perryi (found in northeastern Africa) and Aloe ferox (found in South Africa). But the most popular species is Aloe vera. It was and still is the most commonly-used type of Aloe. The Greeks and Romans used Aloe to treat wounds. In the Middle Ages, the yellowish liquid found inside the leaves was favored as a purgative.^{[citation needed]}

Some species, in particular Aloe vera are used in alternative medicines and in home first aid. Both the translucent inner pulp and the resinous yellow exudate from wounding the Aloe plant are used externally to relieve skin discomforts. Systematic reviews of randomised and controlled clinical trials have provided no evidence that Aloe vera has a strong medicinal effect.^[3][4] Other research however suggests Aloe vera can significantly slow wound healing compared to normal protocols of treatment.^[5]

Today, the gel found in the leaves is used for soothing minor burns, wounds, and various skin conditions like eczema and ringworm. The use of this herbal medicine was popularized in the 1950s in many Western Countries. The gel's effect is nearly immediate; it also applies a layer over wounds that is said to reduce the chance of any infection.^[5]

There have been very few properly conducted studies about possible benefits of Aloe gel taken internally, since the extract is toxic, yet it has been found to be anti-carcinogenic.^{[citation needed]} Data also suggest that components of Aloe inhibit tumor growth.^[6] There have been some studies in animal models which indicate that extracts of Aloe have a significant anti-hyperglycemic effect, and may be useful in treating Type II diabetes. These studies have not been confirmed in humans.^[7]

On May 9, 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.^[8]

Chemical properties

According to W. A. Shenstone, two classes of aloins are to be recognized: (1) nataloins, which yield picric and oxalic acids with nitric acid, and do not give a red coloration with nitric acid; and (2) barbaloins, which yield aloetic acid (C₇H₂N₃O₅), chrysammic acid (C₇H₂N₂O₆), picric and oxalic acids with nitric acid, being reddened by the acid. This second group may be divided into a-barbaloins, obtained from Barbados Aloe, and reddened in the cold, and b-barbaloins, obtained from Socotrine and Zanzibar Aloe, reddened by ordinary nitric acid only when warmed or by fuming acid in the cold. Nataloin (2C₁₇H₁₃O₇·H₂O) forms bright yellow scales. Barbaloin (C₁₇H₁₈O₇) prismatic crystals. Aloe species also contain a trace of volatile oil, to which its odour is due.^{[citation needed]}

Popular culture

Aloe rubrolutea occurs as a charge in heraldry, such as in the Civic Heraldry of Namibia.^[9]

Species

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

• Aloe vera - used in healthcare & health products
• Aloe arborescens - used in healthcare
• Aloe aristata - Torch Plant, Lace Aloe
• Aloe dichotoma - quiver tree or kokerboom
• Aloe nyeriensis
• Aloe variegata - Partridge-breasted Aloe, Tiger Aloe
• Aloe barbadensis - Barbados Aloe, Common Aloe, Yellow Aloe, Medicinal Aloe. This is the variety used medicinally.
• Aloe wildii

Trivia

An Aloe tree appeared on stamps issued in 1919 by Batum, a semi-autonomous region of Georgia in the South Caucasus region.

See also

• List of Aloe species
• List of Southern African indigenous trees

References

External links

• Etymology of Aloe
• "Aloe in Flora of North America @ efloras.org". Retrieved on 2008-01-24.

Images

Aloe arborescens	Aloe aristata	Aloe dichotoma	Aloe hereroensis
Aloe parvula	Aloe peglerae	Aloe maculata (A. saponaria)	Aloe maculata flower
Aloe sophie	Aloe speciosa	Aloe striatula	Aloe rauhii

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Source: adapted by the editor from Wikipedia, the free encyclopedia; from the article "Aloe". Image Credit.

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