Wood’s cycad (Encephalartos woodii)

Description

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Wood’s cycad fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
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Wood’s cycad description

In 1895, a single clump of an unknown cycad species was discovered by John Medley Wood on the edge of a forest in South Africa. Over the next two decades, all four stems of Wood’s cycad were removed from the wild and taken into cultivation ^{(1) (2) (4)}. To date, a second wild plant has never been discovered, but the successful cultivation of offsets of the original plant, has ensured the ex-situ preservation of this enigmatic species ^{(2) (4)}.

In addition to its rarity, the striking appearance of Wood’s cycad has made it one of the most sought after cycad species in the world. Growing up to six metres in height, the majestic trunk is topped with an umbrella-shaped crown of two to three metre long, glossy, dark-green leaves ^{(2) (4)}. In mature specimens, the trunk may branch in the crown, and, atypically for cycads, broaden towards the base to form a kind of buttress that supports the plant’s vast weight ⁽²⁾. In common with all cycads, the woody trunk is mostly comprised of soft, pithy storage tissue protected by a solid layer of old leaf bases ^{(4) (5)}. Owing to their common origin, all the Wood’s cycads in cultivation are male, and consequently only produce the pollen bearing male cones. The bright-orange male cones are cylindrical in shape and can grow up to 1.2 metres in length ⁽²⁾.

Size

Max height: up to 6 m ⁽²⁾

Wood’s cycad biology

Given the circumstances of its discovery, it is not surprising that very little is known about the natural history of Wood’s cycad. Nonetheless, cycads in general share a number of common traits. All cycads are long-lived, slow-growing plants that bear their reproductive organs in cones on separate plants, with male cycads bearing cones that contain pollen, and female cycads producing cones that contain ovules that later become seeds ^{(4) (5) (6)}. For a long time cycads were thought, like cone-producing conifers, to be entirely wind pollinated ⁽⁷⁾. However, studies now suggest that the vast majority, if not all cycads, are actually pollinated by insects or more specifically weevils ^{(4) (5) (7)}.

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, which inadvertently help to disperse the seeds ⁽⁵⁾.

Wood’s cycad range

The original plant was discovered on the fringes of the Ngoye Forest in KwaZulu-Natal, South Africa ^{(1) (2)}. There are now around 500 individual male plants, propagated from the original plant, existing in numerous botanical gardens and private collections around the world ^{(2) (4)}.

Wood’s cycad habitat

Originally found on a steep south facing slope ⁽²⁾.

Wood’s cycad status

Classified as Extinct in the Wild (EX) on the IUCN Red List ⁽¹⁾ and listed on Appendix I of CITES ⁽³⁾.

Wood’s cycad threats

It is not known what drove Wood’s cycad to extinction in the wild, or indeed if it ever was abundant. There is some speculation that the original plant discovered by John Medley Wood was a mutation of another cycad, Encephalartos natalensis, or a naturally occurring hybrid of E. natalensis and E. ferox ⁽²⁾. It is therefore possible that there were never more than a few wild specimens ⁽⁸⁾.

Wood’s cycad conservation

Although the area in which the original Wood’s cycad was discovered is well explored, it is yet to be thoroughly surveyed. Consequently, there is still hope that a female plant will eventually be found to reproduce with the growing population of male clones in cultivation. Alternatively, there is a remote possibility that one of the plants in cultivation will undergo a spontaneous sex change, as has been documented in a few cases in other cycad species. In the meantime, efforts are being made to create a female plant by crossing Wood’s cycad with the closely related E. natalensis. By successively backcrossing the female hybrid offspring with male Wood’s cycads, the aim is to eventually produce a ‘pure’ female. However, because it generally takes cycads many years to reach sexual maturity, this is likely to be a lengthy endeavour ^{(2) (4)}.

Authentication

Glossary

Ex-situ

Measures to conserve a species that occur outside of the natural range of the species. For example, in zoos or botanical gardens.

Offsets

In cycads, the vegetative growth of additional stems from the base of an existing stem.

Pollinated

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.

References

1. IUCN Red List (December, 2008)
   http://www.iucnredlist.org/
2. PlantZAfrica (March, 2009)
   http://www.plantzafrica.com/plantefg/encephalten.htm
3. CITES (December, 2008)
   http://www.cites.org
4. Whitelock, L.M. (2002) The Cycads. Timber Press, Portland, Oregon.
5. The Cycad Pages (November, 2008)
   http://plantnet.rbgsyd.nsw.gov.au/PlantNet/cycad/index.html
6. Royal Botanic Gardens, Kew (March, 2009)
   http://www.kew.org/plants/cycads/index.html
7. Jolivet, P. (2005) Cycads and beetles: recent views on pollination. The Cycad Newsletter, 28: 3 - 7.
8. Royal Botanic Gardens, Kew (March, 2009)
   http://www.kew.org/plants/temperate/encephalartos.html