Geography and distribution
Aloe vera is cultivated around the world. It has escaped from cultivation and become naturalised in the Mediterranean, north Africa, the Indian subcontinent, South America and the Caribbean.
Painting of Aloe vera by Marianne North (505: Common Aloe in Flower, Tenerife)
Overview: Aloe vera is a short-stemmed shrubby aloe, frequently suckering and forming dense clumps.
Leaves: The leaves are succulent, erect, forming a dense rosette. The leaves are greyish green, growing to about 50 cm long, with margins that are pinkish with many small spines. The leaf surfaces are sometimes marked with white flecks or spots.
Flowers: The flowers are yellow, tubular, and up to 3 cm long, with anthers and stigma protruding. The flowers are borne in cylindrical racemes on a branched panicle up to 90 cm tall.
Aloe vera was formerly classified as part of the Asphodelaceae family, but this is now included in Xanthorrhoeaceae.
Aloe vera has been used for centuries and it is more popular today than ever. It is cultivated around the world as a crop for its colourless jelly-like leaf parenchyma known as 'aloe gel'. It is used for a variety of purposes in food, food supplements, herbal remedies and cosmetics.
Aloe vera leaf parenchyma (aloe gel) may be effective when used on the skin against psoriasis, burns, frostbite, and sores caused by the Herpes simplex virus. Research has shown that, taken orally, aloe gel can help to lower cholesterol levels in people with high cholesterol, and can help to lower blood glucose levels in people with type II diabetes.
Aloe vera, growing at the Desert Botanic Garden in Phoenix, Arizona (Photos: Olwen Grace)
The green outer layer of the leaves of Aloe vera yields a bitter, yellow exudate which has very different properties from those of the colourless parenchyma. The bitter leaf exudate has traditionally been used as a laxative. However, research has indicated that the active constituents may have harmful effects and can interact with other medicines and herbal remedies. It should not be given to children or to pregnant or breastfeeding women.
Threats and conservation
Aloe vera is naturalised around the world and is common in cultivation. It is not considered to be threatened.
Aloe vera is easy to cultivate, with no special requirements. It should be grown in a well-draining gritty mix. The compost should be soaked when watering during the growing season, and allowed to dry out between waterings. It can be grown in a cool/warm glasshouse and put outside for the summer. Plants can offset profusely, so propagation is by potting up offsets.
Collecting aloe leaf exudate for chemical evaluation in the Jodrell Laboratory at Kew (Photo: Olwen Grace)
Aloe vera at Kew
Aloe vera, and other Aloe species, can be seen growing in the Princess of Wales Conservatory.
Behind the scenes, scientists in the Herbarium and Jodrell Laboratory at Kew have been carrying out research on Aloe vera and its relatives in the genus Aloe for decades and have published on topics such as the chemistry of the leaves, taxonomy, hybridisation, genetics and leaf surface sculpturing.
Read Kew Science blog 'Unravelling the evolutionary history of Aloe vera and its relatives'