Cycad (Encephalartos whitelockii)

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Encephalartos whitelockii
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Cycad fact file

Cycad description

KingdomPlantae
PhylumTracheophyta
ClassCycadopsida
OrderCycadales
FamilyZamiaceae
GenusEncephalartos (1)

Encephalartos whitelockii is a large, spectacular species endemic to a single location, where it forms one of the largest and most impressive cycad populations in Africa (4) (5).  The stems typically grow in large clumps, and although woody in appearance, are mostly comprised of soft, pithy storage tissue protected by a solid layer of old leaf bases. Each stem is topped with a crown of long, dark green, glossy leaves which curve gently backwards (2). The reproductive organs of cycads take the form of cones, similar in appearance to those of a conifer (6), with the male and female cones being borne on separate plants (7). Male plants of E. whitelockii produce up to five, pendulous, bluish-green cones per stem, while female plants produce up to three, bluish-green egg-shaped cones (2).

Size
Trunk length: 4 m (2)
Trunk diameter: 35 - 40 cm (2)
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Cycad biology

Cycads are long-lived, slow growing plants that always occur as individual male or female plants (2) (7). There is no way of determining the sex of a cycad until it begins to produce its first cone (7). For a long time cycads were thought, like cone-producing conifers, to be entirely wind pollinated (8). However, studies now suggest that the vast majority, if not all cycads, are actually pollinated by insects or more specifically weevils (2) (7) (8). To attract pollinators, male and female cones produce powerful odours, usually in the early morning or evening (7). Travelling between the sexes, the weevils pollinate the plants by inadvertently transferring pollen from the male cones to the receptive ovules of the female cones (7) (9).

The seeds produced by cycads are large and have a fleshy outer coat, but are relatively short-lived and vulnerable to desiccation. The fleshy outer layer is desirable to a range of animals such as birds, rodents and bats, depending on the species of cycad and region it occupies. However, with any luck the unpalatable seed is discarded some distance away from the parent plant in a hospitable environment in which to germinate (2). The seeds of E. whitelockii are an important food source for baboons (10).

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Cycad range

Endemic to the Mpanga Gorge on the escarpment of the Albertine Rift Valley in Uganda (4).

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Cycad habitat

This cycad is found in forest along the Mpanga River (5).

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Cycad status

This cycad is classified as Critically Endangered (CR) on the IUCN Red List (1) and listed on Appendix I of CITES (3).

IUCN Red List species status – Critically Endangered

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Cycad threats

By far the greatest threat to E. whitelockii is the ongoing construction of a hydro-electric power station, and an associated dam, above the Mpanga Falls. The development of this new power station will almost certainly result in the elevation of this cycad’s Red List status, as a large proportion of the population will be wiped out (4). The activities of local communities pose an additional threat, with seasonal fires and deliberate felling being particularly problematic (10).

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Cycad conservation

Encephalartos whitelockii is partially protected by its listing on Appendix I of CITES, which permits international trade in this species only under exceptional circumstances (3). In addition, part of the E. whitelockii population occurs within the boundary of the Queen Elizabeth National Park, although the integrity of some of Uganda’ protected areas is a moot point (4). Owing to the increased pressure on E. whitelockii, a local community-based conservation project is fortunately being implemented in the region. The project is aiming to raise community awareness on the conservation and importance of the species, as well as to create a seed bank and nursery. The propagation of E. whitelockii in a nursery will provide plants for replanting in the wild to bolster the population (10). With the population under as serious threat as it is, projects like this may be critical to this species survival.

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Find out more

For further information on the conservation of cycads in South Africa see:

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Authentication

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

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Glossary

Endemic
A species or taxonomic group that is only found in one particular country or geographic area.
Germinate
The beginning of growth, usually following a period of dormancy and in response to favourable conditions. For example, the sprouting of a seedling from a seed.
Ovules
A structure within the female reproductive organs of plants that contains eggs and when fertilized by pollen, develops into seeds.
Pollinate
To transfer pollen grains from the stamen (male part of a flower) to the stigma (female part of a flower) of a flowering plant. This usually leads to fertilisation, the development of seeds and, eventually, a new plant.
Pollinators
Animals that in the act of visiting a plant's flowers transfer pollen grains from the stamen (male part of a flower) to the stigma (female part of a flower) of a flowering plant. This usually leads to fertilisation, the development of seeds and, eventually, a new plant.
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References

  1. IUCN Red List (April, 2011)
    http://www.iucnredlist.org
  2. The Cycad Pages (February, 2010)
    http://plantnet.rbgsyd.nsw.gov.au/PlantNet/cycad/index.html
  3. CITES (February, 2010)
    http://www.cites.org
  4. Roberts, A. (2008) New threat to Uganda’s cycads. Oryx, 42: 325.
  5. Palm and Cycad Societies of Australia (PACSOA) (February, 2010)
    http://www.pacsoa.org.au/cycads/Encephalartos/whitelockii.html
  6. Royal Botanic Gardens, Kew (February, 2010)
    http://www.kew.org/plants/cycads/index.html
  7. Whitelock, L.M. (2002) The Cycads. Timber Press, Portland, Oregon.
  8. Jolivet, P. (2005) Cycads and beetles: recent views on pollination. The Cycad Newsletter, 28: 3-7.
  9. Donaldson, J.S. (1997) Is there a floral parasite mutualism in cycad pollination? The pollination biology of Encephalartos villosus (Zamiaceae). American Journal of Botany, 84: 1398 - 1406.
  10. The Rufford Small Grants for Nature Conservation (February, 2010)
    http://www.ruffordsmallgrants.org/rsg/projects/dennis_kamoga
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Image credit

Encephalartos whitelockii  
Encephalartos whitelockii

© Kyle Wicomb

Kyle Wicomb
kylecawaza@yahoo.com
http://www.flickr.com/photos/36838058@N03/

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