An evergreenperennial, it originates from the Arabian Peninsula, but also grows wild in tropical, semi-tropical, and arid climates around the world.[4] It is cultivated for commercial products, mainly as a topical treatment used over centuries.[4][5] The species is attractive for decorative purposes, and succeeds indoors as a potted plant.[6]
The leaves of Aloe vera contain significant amounts of the polysaccharide gel acemannan, which can be used for topical purposes.[7] Aloe skin contains aloin which is toxic. Products made from Aloe vera usually only use the gel.
There are many products containing aloe vera's acemannan, including skin lotions, cosmetics, ointments and gels for minor burns, skin abrasions, insect bites, and windburn.[8]
Oral ingestion of aloe vera extracts can be dangerous, because it causes reactions which are not yet fully understood.[5][9] It is especially dangerous for pregnant women; some people have allergic reactions, even when the aloe vera is applied only to the skin.[5][9]
Etymology
Teeth on the leaf edges
The genus name Aloe is derived from the Arabic word alloeh, meaning "bitter and shiny substance" or from Hebrewאוהליםahalim, plural of אוהלahal.[10][11][12] The specific epithetvera comes from verus meaning "true" in Latin.[11][13]
Common names
Common names use aloe with a region of its distribution, such as Chinese aloe, Cape aloe or Barbados aloe.[5][14][15]
Taxonomy
The species has several synonyms: Aloe barbadensis Mill., Aloe indica Royle, Aloe perfoliata L. var. vera and Aloe vulgaris Lam.[2][16][17] Some literature identifies the white-spotted form of Aloe vera as Aloe vera var. chinensis;[18][19] and the spotted form of Aloe vera may be conspecific with A. massawana.[20] The species was first described by Carl Linnaeus in 1753 as Aloe perfoliata var. vera,[21] and was described again in 1768 by Nicolaas Laurens Burman as Aloe vera in Flora Indica on 6 April and by Philip Miller as Aloe barbadensis some ten days after Burman in the Gardener's Dictionary.[22]
Techniques based on DNA comparison suggest Aloe vera is relatively closely related to Aloe perryi, a species endemic to Yemen.[23] Similar techniques, using chloroplast DNA sequence comparison and inter simple sequence repeat profiling have also suggested it is closely related to Aloe forbesii, Aloe inermis, Aloe scobinifolia, Aloe sinkatana, and Aloe striata.[24] With the exception of the South African species A. striata, these Aloe species are native to Socotra (Yemen), Somalia, and Sudan.[24] The lack of obvious natural populations of the species has led some authors to suggest Aloe vera may be of hybrid origin.[25]
Description
Spotted forms, also named Aloe vera var. chinensisHistorical image from Acta Eruditorum, 1688
Aloe vera is a stemless or very short-stemmed plant growing to 60–100 centimetres (24–39 inches) tall, spreading by offsets.[4]
Leaves
The leaves are thick and fleshy, green to grey-green, with some varieties showing white flecks on their upper and lower stem surfaces.[26] The margin of the leaf is serrated and has small white teeth.
The flowers are produced in summer on a spike up to 90 cm (35 in) tall, each flower being pendulous, with a yellow tubular corolla 2–3 cm (3⁄4–1+1⁄4 in) long.[26][29]
Roots
Like other Aloe species, Aloe vera forms arbuscular mycorrhiza, a root symbiosis that allows the plant better access to mineral nutrients from the soil.[30]
The species was introduced to China and various parts of southern Europe in the 17th century.[36] It is widely naturalized elsewhere, occurring in arid, temperate, and tropical regions of temperate continents.[4][32][37] The current distribution may be the result of cultivation.[20][38]
Aloe vera has been widely grown as an ornamental plant. The species is popular with modern gardeners as a topical medicinal plant[39] and for its interesting flowers, form, and succulence. This succulence enables the species to survive in areas of low natural rainfall, making it ideal for rockeries and other low water-use gardens.[26] The species is hardy in zones 8–11, and is intolerant of heavy frost and snow.[29][40] The species is relatively resistant to most insect pests, though spider mites, mealy bugs, scale insects, and aphid species may cause a decline in plant health.[41][42] This plant has gained the Royal Horticultural Society's Award of Garden Merit.[43]
In pots, the species requires well-drained, sandy potting soil, and bright, sunny conditions. Aloe plants can turn red from sunburn under too much direct sun, though gradual acclimation may help.[44] The use of a good-quality commercial propagation mix or packaged "cacti and succulent mix" is recommended, as they allow good drainage.[45] Terra cotta pots are preferable as they are porous.[45] Potted plants should be allowed to completely dry before rewatering. When potted, aloes can become crowded with "pups" growing from the sides of the "mother plant". Plants that have become crowded can be divided and repotted to allow room for further growth, or the pups can be left with the mother plant.[44] During winter, Aloe vera may become dormant, during which little moisture is required.[44] In areas that receive frost or snow, the species is best kept indoors or in heated glasshouses.[29] Houseplants requiring similar care include haworthia and agave.[44]
There is large-scale agricultural production of Aloe vera in Australia,[46] Cuba, the Dominican Republic, China, Mexico,[47] India,[48] Jamaica,[49] Kenya, Tanzania, South Africa,[50] Spain,[51] and the United States,[52] with much of the output going toward the cosmetics industry.[4]
Uses
Two substances from Aloe vera – a clear gel and its yellow latex – are used to manufacture commercial products.[9][39] Aloe gel typically is used to make topical medications for skin conditions, such as burns, wounds, frostbite, rashes, psoriasis, cold sores, or dry skin.[9][39] Aloe latex is used individually or manufactured as a product with other ingredients to be ingested for relief of constipation.[9][39] Aloe latex may be obtained in a dried form called resin or as "aloe dried juice".[53]
There is conflicting evidence regarding whether Aloe vera is effective as a treatment for wounds or burns.[5][39] There is some evidence that topical use of aloe products might relieve symptoms of certain skin disorders, such as psoriasis, acne, or rashes,[9][39] but topical application may cause an allergic reaction in some people.[11]
Aloe veragel is used commercially as an ingredient in yogurts, beverages, and some desserts,[54] but at high or prolonged doses, ingesting aloe latex or whole leaf extract can be toxic.[5][9][11][15] Use of topical aloe vera in small amounts is likely to be safe.[9][39]
Aloin, a compound found in the semi-liquid latex of some Aloe species, was the common ingredient in over-the-counter (OTC) laxative products in the United States until 2002 when the Food and Drug Administration banned it because manufacturers failed to provide the necessary safety data.[5][9][55]Aloe vera has potential toxicity, with side effects occurring at some dose levels both when ingested and when applied topically.[5][15] Although toxicity may be less when aloin is removed by processing, Aloe vera ingested in high amounts may induce side effects, such as abdominal pain, diarrhea or hepatitis.[5][56] Chronic ingestion of aloe (dose of 1 gram per day) may cause adverse effects, including hematuria, weight loss, and cardiac or kidney disorders.[5]
Aloe vera juice is marketed to support the health of the digestive system, but there is neither scientific evidence nor regulatory approval for this claim.[5][9][39] The extracts and quantities typically used for such purposes are associated with toxicity in a dose-dependent way.[5][11][15]
Traditional medicine
Aloe vera is used in traditional medicine as a skin treatment. Early records of its use appear from the fourth millennium BCE.[5] It is also written of in the Juliana Anicia Codex of 512 CE.[54]: 9
Commodities
Aloe vera is used on facial tissues where it is promoted as a moisturizer and anti-irritant to reduce chafing of the nose. Cosmetic companies commonly add sap or other derivatives from Aloe vera to products such as makeup, tissues, moisturizers, soaps, sunscreens, incense, shaving cream, or shampoos.[54] A review of academic literature notes that its inclusion in many hygiene products is due to its "moisturizing emollient effect".[28]
Use of aloe vera on the skin is generally not associated with significant side effects.[9] Oral ingestion of aloe vera is potentially toxic,[5][11] and may cause abdominal cramps and diarrhea which in turn can decrease the absorption of drugs.[5][9]
^ abcdefghijkl"Aloe vera". National Center for Complementary and Integrative Health, US National Institutes of Health. 1 October 2020. Retrieved 1 July 2021.
^Harper, Douglas (2021). "Aloe". Online Etymology Dictionary. Retrieved 1 July 2021.
^Curwin, David (16 March 2008). "aloe". Balashon - Hebrew Language Detective. Retrieved 16 December 2022.
^Lewis, Charlton T.; Short, Charles (1879). "vērus". A Latin Dictionary. Perseus Digital Library.
^Liao Z, Chen M, Tan F, Sun X, Tang K (2004). "Microprogagation of endangered Chinese aloe". Plant Cell, Tissue and Organ Culture. 76 (1): 83–86. doi:10.1023/a:1025868515705. S2CID41623664.
^"Taxon: Aloe vera (L.) Burm. f." Germplasm Resources Information Network, United States Department of Agriculture. Archived from the original on 24 September 2015. Retrieved 16 July 2008.
^Wang H, Li F, Wang T, Li J, Li J, Yang X, Li J (2004). "[Determination of aloin content in callus of Aloe vera var. chinensis]". Zhong Yao Cai (in Chinese). 27 (9): 627–8. PMID15704580.
^Gao W, Xiao P (1997). "[Peroxidase and soluble protein in the leaves of Aloe vera L. var. chinensis (Haw.)Berger]". Zhongguo Zhong Yao Za Zhi (in Chinese). 22 (11): 653–4, 702. PMID11243179.
^Linnaeus, C. (1753). Species plantarum, exhibentes plantas rite cognitas, ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas. Vol. 2 pp. [i], 561–1200, [1–30, index], [i, err.]. Holmiae [Stockholm]: Impensis Laurentii Salvii.
^Newton LE (1979). "In defense of the name Aloe vera". The Cactus and Succulent Journal of Great Britain. 41: 29–30.
^Darokar MP, Rai R, Gupta AK, Shasany AK, Rajkumar S, Sunderasan V, Khanuja SP (2003). "Molecular assessment of germplasm diversity in Aloe spp. using RAPD and AFLP analysis". J Med. Arom. Plant Sci. 25 (2): 354–361.
^ abTreutlein J, Smith GF, van Wyk BE, Wink W (2003). "Phylogenetic relationships in Asphodelaceae (Alooideae) inferred from chloroplast DNA sequences (rbcl, matK) and from genomic finger-printing (ISSR)". Taxon. 52 (2): 193–207. doi:10.2307/3647389. JSTOR3647389.
^Jones WD, Sacamano C. (2000) Landscape Plants for Dry Regions: More Than 600 Species from Around the World. California Bill's Automotive Publishers. USA.
^ abcYates A. (2002) Yates Garden Guide. Harper Collins Australia
^King GK, Yates KM, Greenlee PG, Pierce KR, Ford CR, McAnalley BH, Tizard IR (1995). "The effect of Acemannan Immunostimulant in combination with surgery and radiation therapy on spontaneous canine and feline fibrosarcomas". J Am Anim Hosp Assoc. 31 (5): 439–447. doi:10.5326/15473317-31-5-439. PMID8542364.
^ abEshun K, He Q (2004). "Aloe vera: a valuable ingredient for the food, pharmaceutical and cosmetic industries—a review". Critical Reviews in Food Science and Nutrition. 44 (2): 91–96. doi:10.1080/10408690490424694. PMID15116756. S2CID21241302.
^ abcBotanica's Pocket Gardening Encyclopedia for Australian Gardeners. Random House Publishers. 2001. ISBN9781740514347. Random House Australia/
^Gong M.; Wang F.; Chen Y (2002). "[Study on application of arbuscular-mycorrhizas in growing seedings of Aloe vera]". Zhong Yao Cai (in Chinese). 25 (1): 1–3. PMID12583231.
^ abcdPeerless, Veronica (2017). How Not to Kill Your Houseplant. DK Penguin Random House. pp. 38–39.
^ abColeby-Williams, J (21 June 2008). "Fact Sheet: Aloes". Gardening Australia, Australian Broadcasting Corporation. Archived from the original on 6 July 2008. Retrieved 8 July 2008.
^ abcReynolds, Tom (Ed.) (2004) Aloes: The genus Aloe (Medicinal and Aromatic Plants - Industrial Profiles. CRC Press. ISBN978-0415306720
^Food Drug Administration, HHS (2002). "Status of certain additional over-the-counter drug category II and III active ingredients. Final rule". Fed Regist. 67 (90): 31125–7. PMID12001972.
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