Aloes have been used as medicinal plants for centuries. Aloe vera was mentioned in the herbal of Dioscorides, produced in the first century CE and an illustration appeared in the Codex Aniciae Julianae, produced in the year CE 512. It was formally named Aloe perfoliata var. vera by Linnaeus in 1753, which is the starting point for flowering plant nomenclature. Reynolds (1966) argued that it was first recognised as a distinct species in 1768 by Miller, who called it Aloe barbadensis. However, Reynolds had overlooked a publication by Burman slightly earlier, perhaps only a few days, in 1768, in which the taxon was called Aloe vera. Therefore the correct name is now Aloe vera (L.) Burm.f. (Newton, 1979). Several other species have also been used to treat both humans and domestic animals. Medicinal uses are covered in other chapters of the present book, but there are also other uses.
Leaves of aloes, especially A. vera, are used in the production of many cosmetic products. This is part of the 'back to nature' movement, whose adherents believe that using natural products derived from plants such as the well-known 'health plant' Aloe vera is a healthy way of life. The many kinds of product on the market include after-shaving gel, a mouthwash, hair tonic and shampoo, skin-moistening gel, and even a 'health drink.' In recent years a brand of washing powder and a brand of toilet paper with 'Aloe Vera' have appeared on the market, apparently with the aim of improving our well being. In some southern states of the U.S.A. vast plantations of A. vera can be seen, supporting this large and very successful business and within the last decade or so plantations of the same species have appeared in South Africa.
In Mali, leaf sap of A. buettneri is said to be used as an ingredient of arrow poison, though this is not a species known as being poisonous. Several species are poisonous, because of the presence in leaves of the hemlock alkaloid y-coniceine (Nash etal., 1992). These species have a characteristic smell usually described as that of mice or rats, for which reason the East African Aloe ballyi is known as 'the rat aloe.' In Kenya and Somalia it is reported that Aloe ruspoliana Baker is used to kill hyaenas by smearing meat with the leaf extract. There are published reports of human deaths resulting from the use of aloe leaves (Verdcourt and Trump, 1969; Drummond etal., 1975; Newton, 2001). In some cases overdoses of the medicinally useful compounds are responsible (Neuwinger, 1960).
Some other uses are also based on the chemical content. An insect repellent can be made by drying and burning aloe leaves and similar preparations are used to protect animals against ticks and stored food against weevils (Reynolds, 1950; Watt and Breyer-Brandwijk, 1962; Newton and Vaughan, 1996). Aloe maculata Medik. was known as A. saponaria (Ait.) Haw. for many years, the specific epithet alluding to the use of the roots to make soap. In South Africa, leaf sap of A. maculata was used in the tanning of garments made from skins (Reynolds, 1950). The leaf exudate of aloes is usually yellow but in some species it rapidly turns purple on exposure to air. Some such species, such as A. megalacantha Baker and A. confusa Engl., are used to dye cloth and for making ink. The ash of dried A. ferox Miller and A. marlothii A.Berg. leaves is an ingredient in snuff prepared in some parts of South Africa.
With the bitter compounds in the leaves, aloes are not regarded as edible, but Reynolds (1950) reported that in South Africa the leaves of A. ferox were used to make a jam. However, flowers of various species are eaten in different parts of Africa. Young flowering shoots of A. kraussii Baker and A. minima Baker are eaten as raw vegetables by Zulus (Gerstner in Reynolds, 1950), who cook the flowers of A. boylei Baker, A. cooperi Baker, and other species as a vegetable (Watt and Breyer-Brandwijk, 1962). It is reported that the flowers of A. zebrina Baker have been used to make cakes (Reynolds, 1950). In West Africa, flowers of A. macrocarpa Tod. are eaten by various tribes, and used as a seasoning herb in cooking (Chevalier in Reynolds, 1966). Newton and Vaughan (1996) report that dried leaf material may be mixed with tea leaves in South Africa.
In many African countries aloes are used in gardens as decorative plants and this may be seen on a smaller scale in other tropical or sub-tropical countries. In Nairobi, the capital of Kenya, the indigenous Aloe ballyi Reynolds and the exotic A. barberae Dyer are used as street trees. Smaller-growing species are popular pot plants for enthusiasts who grow succulent plants as a hobby in many temperate region countries. There has also been some degree of artificial hybridisation, to produce new cultivars. Hybrids of smaller-growing species, suitable for pot cultivation, have been produced in Australia, the U.K. and the U.S.A. The miniature Madagascan species are especially popular for this purpose. Larger-growing species have been hybridised in South Africa to produce some spectacular garden plants. Many cultivar names have been published, and many cultivars have been registered with the South African Aloe Breeders' Association, which is the recognised international registration agency.
Where the climate is suitable, some shrubby species are grown as hedge plants. The use of aloes for hedging in South Africa was reported by Carl Peter Thunberg in 1795, and today A. arborescens Miller and A. ferox are seen planted around cattle pens. In East Africa Aloe dawei A.Berg. and A. kedongensis Reynolds are used as hedges (Figure 1.3) and closely planted A. rivae plants have also been used as boundaries.
In Kenya, A. chrysostachys is planted in rows on eroded slopes in an attempt to protect the soil (Figure 1.4).
Arborescent aloes are not regarded as timber plants, but in the absence of more suitable plants in the area, stems of the Madagascan A. vaotsanda Decary are used locally for building huts. Branches of the South African A. dichotoma are used to make quivers for arrows, giving this species the vernacular name 'quiver tree' (first reported by Simon van der Stel in 1685). In more modern times the hollow dead stems are cut into pieces to make various decorative items, such as ash trays and other small containers. The spiny leaves of A. marlothii are used for scraping and thinning animal hides to prepare them for making garments (Reynolds, 1950).
As with many other succulent plants noted for their unusual or even bizarre appearance, aloes have been used in various activities relating to superstition (Reynolds, 1966). Aloe products, such as dried leaves, have been found amongst the items used for fetish purposes by traditional priests and witch-doctors. As uprooted aloes can survive for years, and even flower in this condition, they are often hung over doors of houses as charms intended to ensure long life for the occupants. An uprooted A. aristata Haw. plant
in the home of a childless woman in Botswana is supposed to indicate whether or not the woman will bear a child, according to whether the plant flowers or dries up. Several species, such as A. rivae and A. vera, are planted on graves. In southern Africa a Sotho man maintained a plant of A. arborescens as the home of the spirits of his male ancestors (Jackson, 1964). Aloe maculata is used to prepare a charm against lightning. Another supposed protective function is that A. ecklonis Salm-Dyck is used as a charm to turn enemy bullets into water drops (Watt and Breyer-Brandwijk, 1962). Watt and Breyer-Brandwijk (1962) report that young female initiates in South Africa bathe with a lotion prepared from A. kraussii, though perhaps this overlaps with a possible medicinal value for the skin.
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