by Bruce Brethauer
The aloes are a remarkably diverse group of old world succulents, mostly native to Africa, and Madagascar, but also present in Socotra, and the Arabian peninsula. Few persons are aware of the remarkable number of aloe species (some taxonomists recognize over 400 species) ranging in size from the tree-like Aloe dichotoma, and A. barberae to more or less shrubby species producing a large rosette of succulent leaves on top of short trunks, to the more miniature species, growing from a few inches tall to perhaps 1 to 2 feet in height. These smaller species have been widely grown as house plants, and in suitable climates, as attractive drought tolerant groundcovers and accents in the xeric garden. Some of the larger species are also incorporated in desert gardens and xeriscapes, and are especially appreciated for their stunning appearance, and for their spikes and racemes of flowers, which are often large and vibrantly colored in various combinations of yellows, pinks, orange and reds - depending upon the species and variety. The Aloes are closely related to the genus Knifofia (the "Red Hot Pokers") and due to close similarities in their flowers, and studies of their genetics, some Taxonomists have suggested that the two genera should be combined under the genus Aloe.
Most people are familiar with Aloe vera, the so-called "Burn Plant", famous for its soothing properties in the treatment of minor burns and skin abrasions. The documented use of Aloe vera in the treatment of skin injuries and diseases goes back about 3600 years (it is first recorded in the Ebers Papyrus from 16th century BC). The species has been widely cultivated through the passing centuries, with many naturalized stands identified throughout southern Arabia, Mediterranean Africa and Europe, the Sudan, the Canary Islands and even China (where it has been cultivated for about 400 years or more). Curiously, there are no known native stands of this species, so its place of origin, and original distribution remains a mystery to this day. Some authorities have suggested that Aloe vera may actually be a natural hybrid, and may never have had much of a distribution prior to the time that humans discovered its more useful traits. DNA comparisons reveal that the closest relatives of this plant includes similar species (Aloe forbesii, Aloe inermis, Aloe scobinifolia, Aloe sinkatana, and Aloe striata) most of which are native to Socotra. Somalia, and Sudan, suggesting that this region is the most likely region for the origin of this species.
The wide distribution of this plant today is exclusively due to the activity humans, who have transported and grown it for its use in medicine. Today, it is widely grown throughout the tropical and sub tropical regions in plantations where it is harvested to provide aloe gel for skin care products, and as an additive to foods and other products.
Of all the succulents which have been grown as houseplants, I suspect that Aloe vera is the most widely grown and popular. It is an easily grown plant, offering few challenges to the grower. It is very tolerant of neglect, does not require frequent attention, possesses no dangerous spines or toxins, and best of all, it is regarded as a highly useful plant - people like to have it on hand to treat the occasional burn or scrape. No other succulents enjoy such a popularity, although there are a number of other succulent plants which have been employed in a similar manner to treat skin irritations: the de-thorned and filleted pads of Prickly Pears (Opuntia species) have been used as a dressing for minor wounds and as a poultice. The crushed leaves of sempervivum ("Hens and Chicks") have also been used to sooth minor skin irritations, and the juice from their leaves has been used in the treatment of ear-aches. The leaves of many types of the larger leaved sedum have also been employed to sooth skin irritations. Even so, Aloe vera seems to remain the hands down favorite as an herbal remedy for the treatment of burns.
Curiously, the scientific evidence on the healing properties of Aloe gel is a bit of a mixed bag. Some studies support its role as an aide to healing - helping the body heal faster, while other studies indicates that the use of Aloe gel will actually delay the healing process. Anyone who has ever applied the fresh cut leaves or leaf juices of this plant to a burn or scrape knows that it produces an immediate soothing sensation - so whether or not it actually promotes a faster healing process may be immaterial - it will always be useful to take some of the sting out of minor burns and scrapes.
There are two basic growing forms of this plant in cultivation. Most plants are of the Chinese form, a smaller growing plant which has a good amount of spotting on its leaves; these plants typically grow to about a foot tall, and tend to produce lots of offsets at their base. In time, this form will fill a pot with multiple offsets. The leaves are practically the consistency of ripe grapes - they are very juicy, without much internal fiber to provide support. This variety has the tendency to produce fans and rosettes which may eventually flop to the ground as the plant becomes too tall to support its own weight.
Clones from northern Africa are more robust plants, with somewhat more rigid leaves and stems; there is practically no spotting on their leaves. These can grow to about 2 or 3 feet tall, and may be somewhat less prone to fill the pot with a multitude of offsets (although it will readily produce offsets). Both plants are used to sooth skin irritations, although the smaller version is probably the most frequently grown as a houseplant (its smaller size makes it more suitable for the windowsill). The larger sized variety is probably the one preferred in plantations where it is grown for the production of aloe gel.
Aloe vera responds well to my general guidelines for growing succulents, with a few minor modifications: while it prefers very bright light, my recommendation to move it outdoors into full sun during the warm months of spring, summer, and fall may not be best for this plant - it will probably do best in a site where it can get some afternoon shade. In full sun - especially in regions of the "Sun Belt" the leaves will take on a decidedly bleached appearance - in Tucson, I saw plants of this species in the landscape which were virtually scorched from the intense sun of that region. For plants which are grown exclusively indoors, I continue to recommend that this plant should be provided with the brightest setting possible. Also, it may prefer somewhat warmer conditions during its winter dormancy - to a low of about 60 degrees may be best, although it will survive colder conditions (it is rated to a zone 8 so it will tolerate a light frost in the garden, although extended sub-freezing conditions and hard frosts will kill it outright). This species seems to tolerate more frequent watering, but overwatering can and will kill this plant - do not keep it perpetually moist - let the soil dry out before re-watering. Finally - grow this plant in something other than any generic potting mix - this is the first plant which I tested using Moo-Nure as a potting medium, and the resulting growth was quite impressive - give it a try and see for yourself.
Admittedly, Aloe vera is a bit of a "plain Jane" - the plants all by themselves do not have a lot of the beauty or character to be found in other aloe species, and their flowers are a bit on the small size, and are a bit less vibrant than some other aloe species. Because they are so common, and widely grown, true aficionados often disregard this plant altogether, preferring species with a bit more visual appeal, but this species is one of the great "entry level" succulents - widely known and grown and recognized. It is one of a very few plants which novices can ask for by name, and find readily - practically any store which has a display of cactus plants will also have a tray or two of Aloe vera plants - no need to search the web, or put in an order to a mail order nursery. These are easy to grow, and are useful plants to have around the house and require so little daily attention that most growers have few problems in maintaining them. After growing this plant for a while - many growers will get interested in trying a few of the "other" aloes.