Tuesday 18 June
Cactus (Melocactus pachyacanthus)
ENDANGEREDCactus fact file
- Description
- Biology
- Range
- Habitat
- Status
- Threats
- Conservation
- Find out more
- Glossary
- References
- Print factsheet
Cactus description
| Kingdom | Plantae |
| Phylum | Tracheophyta |
| Class | Magnoliopsida |
| Order | Caryophyllales |
| Family | Cactaceae |
| Genus | Melocactus (1) |
Melocactus pachyacanthus is a squat, rounded cactus. Two subspecies are recognised which differ in the appearance of their stems; M. p. subsp. pachyacanthus has a waxy bluish-green sheen and woolly areoles, whilst M. p. subsp. viridis lacks wool and may have a waxy covering only when young (2). The stem is distinctively crowned by a concentration of dull pinkish-red bristles known as a 'cephalium', which may reach up to 30 centimetres high and 10 centimetres in diameter (2). This feature is characteristic of cacti from the genera Melocactus and Discocactus (4). The stem of the cactus has 9 to 11 low ribs, bearing rows of areoles from which stout reddish spines extend (2). Deep pink-red flowers are produced although they barely extend beyond the cephalium; following fertilisation, pale, cylindrical fruits develop (2).
- Size
- Height: 15 - 30 cm (2)
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Related species
Cactus biology
Hummingbirds pollinate the flowers of this cactus and the fruits are probably distributed by lizards (2).
TopCactus range
Endemic to Bahia State in eastern Brazil, this species has a restricted range within the Rio São Francisco drainage basin in the northern part of the State (2).
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Species with a similar range
Cactus habitat
Melocactus pachyacanthus inhabits the dry thorny forests region of eastern Brazil known as caatinga vegetation (2). It is usually associated with exposed limestone rocks (2).
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Species found in a similar habitat
Cactus status
Classified as Endangered (EN) on the IUCN Red List 2007 (1), and listed on Appendix II of CITES (3). Subspecies: Melocactus pachyacanthus pachyacanthus is classified as Endangered (EN) and Melocactus pachyacanthus viridis classified as Critically Endangered (CR) on the IUCN Red List 2007 (1).
Cactus threats
Habitat destruction is widespread in the caatinga region of eastern Brazil; over the centuries, forests have been cleared for fuel and for the conversion of the land to agriculture (2). As a result, M. p. subsp. viridis has now been lost from all but a single site within its former range, where, as of 2003, fewer than 50 individual plants survive (2).
TopCactus conservation
International trade in wild-taken Melocactus pachyacanthus is restricted by its listing on Appendix II of the Convention on International Trade in Endangered Species (CITES) (3). The largest population of M. p. subsp. pachyacanthus numbers over 1000 individuals and is fully protected within the Gruta dos Brejoes protected area (2). The future of M. p. subsp. viridis is far from secure however, and urgent field research is needed in the hope of discovering new populations of this subspecies (2). A greater network of protected areas within the vast caatinga region is a conservation priority if its endemic species are going to persist.
TopFind out more
For more information on Brazilian cacti see:
- Taylor, N.P. and Zappi, D.C. (2004) Cacti of Eastern Brazil. Royal Botanic Gardens, Kew.
Authentication
Authenticated (20/3/03) by Dr Nigel Taylor, Royal Botanic Gardens, Kew.
http://www.rbgkew.org.uk
Glossary
- Areoles
- In cacti, the felted or woolly, cushion-like structures from which spines grow, flowers develop and new stems arise.
- Endemic
- A species or taxonomic group that is only found in one particular country or geographic area.
- Fertilisation
- In a flowering plant, fertilisation is the process of a pollen grain joining with the ovule (female egg cell). After fertilisation, the female parts of the flower develop into a fruit.
- Subspecies
- A different race of a species, which is geographically separated from other populations of that species.
References
- IUCN Red List (February, 2003)
http://www.iucnredlist.org - Taylor, N.P. and Zappi, D.C. (2004) Cacti of Eastern Brazil. Royal Botanic Gardens, Kew.
- CITES (February, 2003)
http://www.cites.org - Hewitt, T. (1993) The Complete Book of Cacti and Succulents. Dorling Kindersley, London.
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Saturday 15 June
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Image credit
Melocactus pachyacanthus pachyacanthus with distinctive cephalium
© Nigel P. Taylor / Royal Botanic Gardens, Kew
Royal Botanic Gardens, Kew
Richmond
Surrey
TW9 3AB
United Kingdom
Tel: +44 (0) 208 332 5000
Fax: +44 (0) 208 332 5197
info@kew.org
http://www.rbgkew.org.uk
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