Biological Diversity 2003 Earlham banner


aloe plant
This photo courtesy of  Botany, University of Wisconsin

Taxonomy:

Kingdom:
 Plantae

Phylum:
 Anthophyta

Class:
 Monocotyledonae

Subclass:
 Liliidae

Order:
 Liliales

Family:
 Aloeaceae

Genus:
 Aloe

Species:
 Barbadensis 
 

Aloe plant in flower

Detail of flowers on aloe plant. Photo courtesy of Agriculture, University of Arizona

Conservation Organizations

U.S. Fish and Wildlife Service

  Federal organization; maintains a list of endangered species eligible for protection under the U.S. Endangered Species Act


Red List of Threatened Species

An international list of threatened and endangered species maintained by the Species Survival Commission

CITES
List maintained by the Convention on International Trade in Endangered Species of Wild Fauna and Flora. International agreement regulating trade in endangered and threatened species.

Aloe plant in flower
This image of an aloe plant in flower is courtesy of Agriculture, University of Arizona

aloe ferox
A specimen of Aloe ferox, a close relative of Aloe barbadensis, Photo courtesy of http://www.wits.ac.za/
pharmacy/Pcognosyweb/
onographexample.htm

Aloe Vera (Aloe barbadensis)

Aloe Plant
This photo courtesy of http://www.blankees.com/house/plants/aloe_b.htm

Introduction

Distribution and Habitat:

A. barbadensis is native to warm, dry regions, especially southern Europe, Asia, and Africa (University of Wisconsin, 1999). It is cultivated almost everywhere in the world, both as a houseplant and for its medicinal qualities. It grows best in full sunshine and does not require much water (Denk, 2000). It does not grow well at temperatures below 32 degrees Fahrenheit.

Physical Characteristics:

A. barbadensis can grow up to three feet tall, although most specimens are between one and two feet tall (Gilman, 1999). It has thick leaves that grow in a rosette shape
(Denk, 2000). The parenchyma cells of the leaves contain large quantities of pulp . Aloe is a monocotyledon and a member of the lily family. It is an evergreen.

Lifespan and Reproductive Process:

Aloe is a perennial and takes 4-5 years to mature. Plants can live and reproduce for up to 25 years (Denk, 2000). Its tubular flowers, yellow to red in color, grow in arrow-shaped clusters on spikes that are up to 3 feet tall (Moore, 2001). Aloe flowers in springtime. Its fruits are small and not particularly significant. In addition to propagating via seeds, it can reproduce by offsets, which may take root up to 6 feet away from the plant and grow into new plants (Moore, 2001).

Conservation Status

Aloe barbadensis is not an endangered species. It is not listed on the United States Endangered Species Act list. It is not listed on the internationally maintained Red List of Threatened Species or on the CITES list of endangered species. However, it is closely related to other species that are endangered. According to the CITES list, every species of the genus Aloe, besides A. barbadensis, is threatened, and some are endangered. A. barbadensis is often cultivated domestically and for commercial purposes, but its wild habitat is threatened in the same way as the habitat of the other members of its genus.

Conservation Issues 

As stated previously, A. barbadensis itself is not an endangered species, but is closely related to species that are. Excepting A. barbadensis, trade is restricted in all plants of the Aloe genus due to destruction of their natural habitat. What is this habitat? What is causing the destruction of these plants and their habitat, and what can be done to save it?

Aloe's Habitat:

Aloe species primarily inhabit relatively dry, warm climates. This habitat type is termed "Mediterranean Forests, Woodlands and Scrub" by the World Wildlife Federation. Habitats described include the area surrounding the Mediterranean Sea in Europe and Africa, some parts of the southwestern United States, southern Australia, and the southern parts of Africa, especially South Africa. Aloe is native to the Mediterranean area in Europe and to South Africa, but has been introduced successfully in the southern United States and Australia as well. These climates tend to have warm, dry summers and cool, moist winters, with more precipitation occurring during the winter. Fires occur frequently in summers, and the species that survive are those that tolerate fire and drought well. Nutrient density is low in these regions, and thus the habitat cannot support large predators. Smaller animals and especially plants predominate. These habitats have a wide variety of species that have adapted to these unique ecological conditions. (WWF, 2001) Some, including some species of Aloe, are endemic. Aloe albida, for example, is found in the wild only in South Africa. (Hankey and Lotter, 2002)

Threats To Aloe:

This habitat is faced with destruction due to several factors. One factor is deforestation and settlement of the area by humans. This disrupts the natural balance of the area and threatens the native species, including the aloes (WWF, 2001; 
Hankey and Lotter, 2002). The habitat is also affected by burning. Species that have evolved to survive in this habitat are naturally tolerant of regular fires. Over-burning and under-burning, though, disrupt the ecological balance. Overburning destroys too many of the naturally present nutrients, and underburning leads to too many nutrients, making it easier for non-native species to invade. (WWF, 2001). Invasive plant species pose a real problem by crowding out the native species. Over-grazing by animals also depletes the nutrient stores, and this also occurs when humans disrupt the naturally occurring balance of species in the area. (WWF, 2001). Due to their rarity, aloes and other native plants are valuable as collectors' items, but if too many are taken from the wild, their population is threatened. (Maneveldt). Human needs for water have led to dams being built in some areas of aloe's habitat, and, of course, these artificially-created bodies of water destroy the local ecosystem.

A. barbadensis, and to a lesser extent other aloes, are also heavily used by humans. Aloe has commonly been kept as a houseplant and the sap of the plant has been used to soothe the pain of burns, rashes, insect bites, and other skin irritations. The application of aloe gel to the irritated area increases oxygen flow to the area, helping speed the process of healing. (Waltz, 2002) The sap contains many nutrients, including 7 of the 8 essential amino acids and several vitamins. (Aloe Vera Company UK, 2002)  Aloe gel is also a common ingredient in beauty products such as soap and shampoo (Waltz, 2002). Naturally, supplying the beauty industry requires extensive cultivation of A. barbadensis. This can lead to trouble if too much aloe is harvested from the wild for commercial purposes.

Conserving Aloe:

How can people conserve the natural habitat of A. barbadensis and its Aloe cousins? There are several ways. First of all, those growing aloe for commercial purposes can cultivate it in captivity rather than harvesting from the wild. Artificially cultivated aloe plants and seeds can be distributed for commercial and medicinal purposes and as houseplants, and can also be reintroduced into the wild. (
WWF, 2001). The CITES treaty has restricted trade in aloes in order to give the natural population time to regenerate. For populations that are geographically isolated, efforts can be made to connect the populations and facilitate gene flow, thus hopefully making plants more hardy (Hankey and Lotter, 2002). Many steps can be taken to protect the native environment, such as controlled burns of the area, creating nature preserves, and educating the community about the biodiversity of the area and how to take care of it. (WWF, 2001Maneveldt)

Aloe species serve many useful functions and exist in a unique habitat. Care should be taken to make sure that the plants, their habitat, and their community do not die out. If humans are careful with aloe's habitat, we can conserve these extraordinary plants.

Literature Cited


Aloe Vera Company, UK. 2002. Properties of aloe vera constituents. http://www.aloevera.co.uk/aloeprop.htm. Accessed 3 April 2003.
Denk, Maggie. 2000. Plants with human uses. http://www.bio.gasou.edu/Bio-home/Courses/environmental/leege/BOO/ghseontheweb/
humanuses/Humanuses.htm
. Accessed 30 March 2003.
Gilman, Edward F. 1999. Aloe barbadensis. http://hort.ifas.ufl.edu/shrubs/ALOBARA.PDF. Accessed 30 March 2003.
Hankey, Andrew, and Mervyn Lotter. 2002. Cooperative conservation initiative for the preservation of Aloe albida (Stapf.) Reynolds Aloeaceae. (Abstract) http://www.rbg.ca/cbcn/science/abstracts/hankey1.htm. Accessed 3 April 2003.
Maneveldt, Gavin W. Date unknown. Enviro Facts guide to Fynbos. http://www.botany.uwc.ac.za/envfacts/fynbos. Accessed 3 April 2003.
Moore, Toni. 2001. Aloe barbadensis. http://ag.arizona.edu/pima/gardening/aridplants/Aloe_barbadensis.html. Accessed 30 March 2003.
University of Wisconsin, Madison. 1999. Aloe barbadensis. http://botit.botany.wisc.edu/courses/tour/Roomseven-Al.html. Accessed 30 March 2003.
Waltz, Lisa. 2002. Aloe vera-legendary healer. http://www.naturalark.com/aloevera.html. Accessed 3 April 2003.
World Wide Fund for Nature. 2001. Mediterranean forests, woodlands, and scrub.  http://www.panda.org/about_wwf/where_we_work/ecoregions/global200/
pages/habitat/habitat12.htm
. Accessed 3 April 2003.

Author: Elaine Banvard
Creation/revision date: April 4, 2003


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This website is part of a Biology 226 class project on the conservation of global biodiversity.



Earlham· Biology Department · Biology 226: Biological Diversity
Copyright © 2003 Earlham College. Revised 4 April 2003. Send corrections or comments to Elaine Banvard