Succulent plants are of particular interest to the horticulture industry, being naturally desirable to consumers because of their unusual growth forms and characteristics. The ease of care makes them even more popular.
However, succulent plants are not only an important commodity to the multi-million dollar horticulture industry. They are also used for food, fodder, fibers, shelter and are sources of important medicines, drugs, oils, and cosmetics.
The San Bushmen of the Kalahari Desert break off and suck fragments of the succulent Hoodia
The plant is now being investigated by a drugs company with the objective of developing an appetite suppressant drug for the growing obesity market. Negotiations have been carried out between the patent holders and the San elders to secure a benefit-sharing agreement to allow access to profits from a drug market, potentially worth 100’s of millions of dollars.
Succulent plants are traded in large volumes for the horticultural market and by far the majority of these plants are artificially propagated.
Large scale production in the past centered in the industrialized north with Europe, the USA, Canada, and Japan being the prime centers of production. However, over the last decade, a number of other countries have become major players in the global trade.
For example, the Dominican Republic is now a significant exporter of succulent plant taxa. Within Asia, China and the Republic of Korea, are expanding their plant-propagation programmes.
Within Africa, South Africa remains the major center for specialist nurseries propagating native plants. South Africa also cultivates, to a lesser degree, succulents from Madagascar and other African states.
What Groups Are Controlled?
There are four major succulent plant groups covered by CITES – the cactus family (Cactaceae), the succulent Euphorbia species (Euphorbiacae), the genera Aloe (Liliaceae) and Pachypodium (Apocynaceae).
The Cactaceae is by far the largest and best-known group and includes over 2,000 species. There are over 700 succulent species from a total of 2,000 species in the genus Euphorbia, over 400 species in the genus Aloe and 14 species in the genus Pachypodium listed in the Appendices.
The minor succulents listed on CITES are the species Nolina
Three species of Agave (Agavaceae).
All species of the Didieraceae family.
Three species in the genus Fouquieria (Fouquieriaceae).
Two species of the genus Dudleya (Crassulaceae), And all species in the genera Anacampseros (Portulacaceae) and Avonia(Portulacaceae).
The first reports of cultivation of cacti date back to the 1500s. Today, Europe produces millions of propagated cacti per year from its horticultural industry. However, there remains a persistent demand for species collected from the wild.
The entire Cactus family is included in CITES Appendix II, with a number of the most endangered species listed in Appendix I. Cacti are endemic to the Americas with the exception of just one genus, Rhipsalis, whose distribution stretches from South America to southern Africa and Sri Lanka.
The Cactaceae family is characterized by stems which bear specialized felted discs called areoles from which develop spines, an exclusive feature of this plant group.
The ‘hot spot’ for species diversity in Mexico and the adjacent south-western USA where nearly 30% of cacti genera are endemic and nearly 600 species are native. Brazil, northern Argentina, Bolivia, Peru, and Chile are important secondary centers of diversity.
In addition to increasing habitat destruction, illegal collection for international trade continues to be a threat, with new threats emerging all the time.
example, the demand for desert plants for use in landscaping has fuelled the consumer market in succulent plants.
North America estimates that between 1998 and June 2001 nearly 100,000 succulents, with an estimated value of $3 million, were harvested from Texas and Mexico to supply the landscape garden market in Phoenix and Tucson.
The genus Euphorbia includes over 2,000 species, with representatives distributed throughout the world. Their habit ranges from annual plants and shrubs to large trees and succulent species.
Probably the best-known plant in the genus is E.
Most succulent Euphorbia has green, succulent stems and range in size from only a few centimeters tall (E.
Leaves are usually reduced in size and ephemeral, and spines are often present at the stems edges.
In very simple terms succulent Euphorbia has three life forms
All succulent species of Euphorbia, of which there are about 700, are listed in CITES Appendix II. In addition, ten dwarf succulent Madagascan species are listed in CITES Appendix I.
The vast majority of recorded CITES trade in succulent Euphorbia taxa is in live plants for the horticultural industry. This trade is mostly in artificially propagated plants. The Dominican Republic, Haiti, Denmark, Thailand, and South Africa are all major sources of propagated material.
South Africa and Madagascar are the main suppliers of wild plants to the horticultural industry and specialist collector. The CITES trade data show a large variety of wild-collected succulent Euphorbia taxa in a trade with the majority being exported to western Europe, Japan, and the USA.
The major importers of succulent Euphorbia species between 1997 and 2001 were the USA, France, Switzerland, the Netherlands, Germany, China, Canada, and Japan. All of these countries imported more than 10,000 live plants between 1997 and 2001.
However, by far the greatest importer of succulent Euphorbia taxa is the United States of America and the two largest exporters, the Dominican Republic and Haiti, almost exclusively supply this market.
There are over 500 taxa in the genus Aloe, concentrated in southern and eastern Africa and Madagascar. Twenty-two Aloe species are listed in CITES Appendix I. The remainder of the genus, excluding Aloe vera, is listed in CITES Appendix II.
Aloe species can be identified by their characteristic leaf structure. However, their life form varies considerably! Species range from the 20-metre tall “tree Aloes’’ to miniature plants that are only a few centimeters high.
Although Aloe species are generally recognized by their rosettes of succulent leaves and tall, candle-like inflorescences, these characteristics are also a feature of several other succulent genera, such as Agave.
The juices contained within the leaves of some species of Aloe have been used for medicinal and cosmetic purposes for centuries.
Aloe vera, the only Aloe species not covered by the CITES Convention, is propagated worldwide to supply the medicinal and cosmetics industries.
The trade in Aloe is dominated by the cosmetic/medicinal industry and horticulture. South Africa is the major exporter of Aloe plants, parts and derivatives.
As well as artificially propagated plants, South Africa exports significant quantities of wild plants, mainly wild Aloe ferox for the cosmetic/medicinal industry.
South Africa has also exported a range of other wild Aloe taxa, in much smaller quantities, for the horticultural market.
South Africa almost exclusively supplies the demand for wild Aloe leaf extracts (mainly Aloe ferox) for the markets in North America, Europe, and Asia.
In fact, virtually all of the recorded trade in wild plant extracts between 1997 and 2001 has been in Aloe ferox from South Africa. Although not a major exporter of Aloe, Madagascar has also been a source of a range of wild Aloe plants for the horticultural trade.
Canada, the Republic of Korea and Spain have exported the largest quantities of artificially propagated plants. The major markets for live plants are the United States of America, China, and Switzerland.
30 taxa of Pachypodium are accepted in the CITES standard reference for these genera.
These growth forms are in great demand from the specialist collector. The genus Pachypodium is listed in CITES Appendix II, and three species are listed in CITES Appendix I. The Appendix I species are all Malagasy species and were listed in the 1990s due to their rarity and trade demand.
Pachypodium is a genus with a highly restricted distribution. Twenty-three of the 30 accepted Pachypodium taxa listed in the CITES Aloe and Pachypodium checklist are only found in Madagascar. Of the remaining seven taxa included in the checklist, six are found in southern Africa and one is only known in cultivation.
The recorded international trade in Pachypodium is virtually confined to live plants for the horticultural market.
The United States of America is by far the largest exporter of these, shipping large quantities of artificially propagated plants to markets around the world. Canada is the major importer for Pachypodium. Most of its plants originate from the USA.
Most wild Pachypodium taxa in trade originate in Madagascar. European countries (Germany, Norway, Switzerland, and Italy) are the major market for these plant.
Other Succulent Taxa Listed on CITES – Agave, Didieraceae, and Fouquieria
Although there are over 200 species in the genus Agave, only three species are regulated under CITES, not including the species that are used to make tequila!
All of the controlled species occur naturally in the USA or Mexico. There is unlikely to be any problem international trade in these species.
The Didiereaceae is a small family of succulents made up of four genera, Alluaudia, Alluaudiopsis, Decarya, and Didierea. Many taxa have an erect column-like habit similar to columnar Euphorbia or cacti.
They are an important part of the dry thorny forest of southern and south-western Madagascar. They are threatened by habitat clearance, burning, and charcoal production. Demand for wild plants of these taxa for the specialist horticulture trade peaked in the 1980s before propagation became more common.
There are three species in the genus Fouquieria (Fouquieriaceae) listed on the CITES appendices – F. fasciculata and F. purpusii are listed in Appendix I while F. columnaris is included in Appendix II.
The genus includes some 11 species and is confined to Mexico and the Southwest of the USA. In the case of F. columnaris (Boojum tree), it can form dramatic columnar trees up to 18 meters tall and 400 years old.
Fouquieria purpusii and F. fasciculata are smaller shrubs native to Mexico and attractive to the collector. International trade in wild plants outside North America is unlikely.
Other Succulent Taxa Listed on CITES
Anacampseros and Avonia – (formerly included in Anacampseros). There are over 20 species in this group, the majority found in Africa.
The African species are of horticultural interest, with the specialist collection being a potential threat.
However, the current CITES trade data suggests only very low levels of trade. Most noteworthy, there have been reports of illegal trade in Anacampseros
Welwitschia mirabilis live up to 1,500 years!
Welwitschia mirabilis survives on moisture from fog and dew. It was formerly listed in CITES Appendix I but was later downlisted to Appendix II as the plant is relatively common within its habitat and is well protected in its native range.
It is native to Angola and Namibia and is not likely to be traded from the wild, with the possible exception of seeds. Welwitschia mirabilis is the only species in this genus.
It is confined to the shady mossy cliffs of the rivers that drain the Sierra Nevada, in Eastern California, USA.
Dudleya stolonifera and Dudleya
CITES controls and monitors the trade in a number of succulent plants which are important as medicinals. There are twelve species of Aloe (excluding Aloe vera which is no longer CITES controlled), 8 species of Euphorbia, and Dioscorea deltoidea that are recorded as having medicinal uses.
Of the CITES controlled succulents, the most important medicinal plants are Aloe ferox and Dioscorea deltoidea. Native to South Africa and Lesotho, Aloe ferox is used to produce aloe bitters and gels.
The leaves are collected to produce the bitters used in drinks and medicines, and for gels and creams used in skin and hair care products. Aloe bitters are used traditionally as a laxative or purgative, to combat arthritis, and in veterinary medicine.
Aloe-Emodin is reported to have anti-cancer activity in vitro. South Africa is the major exporter and the trade occurs as extract, powders, and leaves.
A report of the Aloe ferox trade by Newton and Vaughan (1996) estimate that the leaves of approximately 17 million plants are harvested annually to produce some 400 tonnes of Aloe bitters.
This trade is considered to be sustainable, as only the leaves are harvested, the plant is relatively common, and a large section of the wild population is never subject to harvesting.
Diosgenin, present in the tubers, is the basis of cortisones, sex-hormones and anti-fertility drugs, including the contraceptive pill.
The production of these drugs has now moved to use synthetic products with limited extraction from plants. International trade in the raw material is now likely to be limited to the Himalayan region.
Although there are reports of trade between Nepal and India there are no official statistics and no CITES trade recorded in the UNEP-WCMC statistics since its listing in 1975.
Almost one-third of cactus species are under threat as a result of over-harvesting and illegal trade in the plants, a global study has concluded.
Conservationists voiced concern, saying the level of threat to cacti was much greater than previously thought.
The plants are a vital component of arid ecosystems, providing a source of food and water for many animals.
The results of the assessment by the International Union for Conservation of Nature appear in Nature Plants journal.
According to the study, 31% of the world’s 1,480 cactus species were under pressure from human activity, such as illegal trading, agriculture, and aquaculture as well as land-use change.
“The results of this assessment come as a shock to us,” said lead author Barbara Goettsch, co-chairwoman of the IUCN’s Cactus and Succulent Plant Specialist Group.
“We did not expect cacti to be so highly threatened and for illegal trade to be such an important driver of their decline.”
The assessment reported that the illegal trade of live plants and seeds for the horticultural industry and private collections, as well as their unsustainable harvesting, affected 47% of threatened species.
These plants which have evolved to cope with the harsh conditions found in arid landscapes are native to North and South America, with exception of one species that is native in southern Africa and South Asia.
Although cacti are a familiar sight in other regions, such as Europe and Australia, these plants have been introduced to these landscapes either intentionally or accidentally.
Many species are highly sought after by collectors for their attractive flowers, and half of the species are used as a source of food or medicine.
Thriving in landscapes where very little vegetation can survive in the intense heat or drought conditions, the cactus group plays a pivotal role in sustaining arid ecosystems.
Among the species that use cacti as sources of food and water are deer, coyotes, lizards, and tortoises. The animals, in return, help distribute the plants’ seeds.
However, Dr. Goettsch told BBC News that cacti species were very isolated.“They tend to occur in very localized places, so the distribution range is generally quite small,” she explained.
“They are also very slow-growing species so this makes them particularly vulnerable to disturbance.” Dr. Goettsch said that extending protected area networks would “definitely benefit the species because we did find that a lot of the threatened species do not occur within protected areas”.
She added that the national-level enforcement of international agreements, such as the Convention on International Trade in Endangered Species of Wild Fauna and Flora (Cites), would help curb the illegal trade in cacti.
“The whole family of cacti is included in Cites, which means that you can trade the species but you need to have permits. This is what needs to be enforced in some of the countries where the species occur,” she said.
“The other thing that would really help these plants would be to raise awareness of the importance of harvesting sustainably because in many cases the plants are not destined for international markets. They are just traded in local markets so many local communities need to be aware of how they should harvest them or if they should harvest them at all.”