Alexandria cycad (Encephalartos arenarius)

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Alexandria cycad
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Alexandria cycad fact file

Alexandria cycad description

KingdomPlantae
PhylumTracheophyta
ClassCycadopsida
OrderCycadales
FamilyZamiaceae
GenusEncephalartos (1)

The Alexandria cycad is a member of an ancient plant group, the cycads, which flourished over 150 million years ago alongside the dinosaurs. Today, there are only around 300 living species of cycad, occupying a small fraction of the group’s former range (4) (5) (6). One of the most attractive of the South African cycad species is the Alexandria cycad, a multi-stemmed, medium-sized plant, with numerous grey-green leaves that recurve towards the tips (2) (6) (7) (8). Although the stems may grow up to two metres long, they are usually partially concealed by sand and leaf mould. As with all cycads, the male and female cones of this species, which are both light green at maturity, are borne on separate plants (2) (8). In addition to the common green leaved form, there is a rarer and smaller blue-leaved form that occurs in a small number of localities (2) (7) (8).

Size
Stem height: 1 - 2 m (2)
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Alexandria cycad biology

Cycads are long-lived, slow growing plants that always occur as individual male or female plants (6) (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 (9). However, studies now suggest that the vast majority, if not all cycads, are actually pollinated by insects or more specifically weevils (6) (7) (9). 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) (10).

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 (6).

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Alexandria cycad range

The Alexandria cycad is restricted to the Alexandria area in the Eastern Cape, South Africa (2) (6) (8).

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Alexandria cycad habitat

Typically grows on sand dunes, within dense mixed shrubland and coastal forest (6) (8).

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Alexandria cycad status

Classified as Endangered (EN) on the IUCN Red List (1) and listed on Appendix I of CITES (3).

IUCN Red List species status – Endangered

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Alexandria cycad threats

Although it was once plentiful across its range, the Alexandria cycad is now relatively rare in the wild, with a population size of just 850 to 1,500 mature individuals (1) (2) (7) (8). Although clearance of habitat for farming was the main cause of its decline in the early 20th century, in more recent times, large numbers of this species have been removed by collectors (7) (8).

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Alexandria cycad conservation

There are not known to be any specific conservation measures in place for the Alexandria cycad, but it is listed on Appendix I of CITES, which permits trade only under exceptional circumstances (3).

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Find out more

For further information on the Alexandria cycad and 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

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 (October, 2009)
    http://www.iucnredlist.org/
  2. PlantZAfrica (October, 2009)
    http://www.plantzafrica.com/plantefg/encepharenarius.htm
  3. CITES (October, 2009)
    http://www.cites.org
  4. Donaldson, J.S. (2003) Cycads, status survey and conservation action plan. IUCN/SSC-Cycad Specialist Group. IUCN, Gland, Switzerland.
  5. Royal Botanic Gardens, Kew (October, 2009)
    http://www.kew.org/plants/cycads/index.html
  6. The Cycad Pages (October, 2009)
    http://plantnet.rbgsyd.nsw.gov.au/PlantNet/cycad/index.html
  7. Whitelock, L.M. (2002) The Cycads. Timber Press, Portland, Oregon.
  8. The Cycad Society of South Africa (October, 2009)
    http://www.cycadsociety.org
  9. Jolivet, P. (2005) Cycads and beetles: recent views on pollination. The Cycad Newsletter, 28: 3 - 7.
  10. 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.
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Image credit

Alexandria cycad  
Alexandria cycad

© Palmbob / Geoff Stein

Palmbob / Geoff Stein
http://davesgarden.com/members/palmbob/

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