Thunberg’s cycad (Encephalartos longifolius)

Description

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Thunberg’s cycad fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
• Print factsheet

Thunberg’s cycad description

Belonging to an ancient group of plants, this ‘living fossil’, has the distinction of being the first cycad to be scientifically recorded in South Africa ⁽⁴⁾. The thick stems of Thunberg’s cycad can reach heights of over 4.5 meters, with mature plants often having up to ten stems, each branching off from the base of the plant ^{(2) (4)}. Young leaves are covered in fine hairs, but overtime, as they grow to lengths of up to two meters, the glossy dark-green to bluish-green leaves become hairless ^{(2) (4)}. The tip of each slender leaf can either be rounded, or terminate in a sharp spine, and sometimes the leaves can have one to three ‘teeth’ on the lower margin ^{(2) (4)}. The enormous cones of Thunberg’s cycad are the heaviest of all South African cycads, with the female cones weighing up to 36 kilograms ⁽⁴⁾. Male plants bear greyish-brown, cylindrical cones, while the female cones are olive-green and egg-shaped ^{(2) (4)}.

Size

Height: 3 – 4.5 m ⁽²⁾

Stem diameter: 30 – 45 cm ⁽²⁾

Thunberg’s cycad biology

Cycads are slow-growing plants that bear their reproductive organs in cones, with male plants bearing cones that contain pollen, and female cycads producing cones that contain ovules that later become seeds ⁽⁵⁾. Thunberg’s cycad produces cones between April and June, and the pollen from the male cone is transferred to a female cone by wind or insects. The exact method by which Thunberg’s cycad is pollinated has not yet been determined, although pollinating beetles have been found on the cones of wild plants ⁽⁴⁾. The fertilized ovules subsequently develop into bright red seeds that are shed between October and December ^{(2) (4) (6)}. Baboons, hornbills and small rodents all feed on the fleshy-covering of the seeds, and through this process, the seeds are dispersed from the parent plant ⁽⁴⁾. As with other cycads, Thunberg’s cycad contains toxic compounds within its tissues, particularly the seeds, and therefore the animals that feed on the seeds must possess a mechanism to counteract the effect of the toxins ⁽⁴⁾.

While it is not clear whether beetles are responsible for pollination of Thunberg’s cycads, the plant definitely has another, important relationship with a beetle species. The cycad weevil Antliarrhinus zamiae uses its snout to burrow into the ovules of Thunberg’s cycad, where it lays its eggs and feeds on the seed kernel ⁽⁷⁾.

Thunberg’s cycad range

Endemic to South Africa, Thunberg’s cycad is widely distributed in the south-western parts of the Eastern Cape Province ⁽⁴⁾.

Thunberg’s cycad habitat

Thunberg’s cycad grows primarily on mountain slopes in fynbos vegetation, at altitudes of 200 to 1,500 metres, where the summers are hot, the winters are cold, and rainfall varies between 300 and 1,250 millimetres ⁽²⁾. It can also be found growing in grasslands and in succulent thicket vegetation ⁽⁴⁾.

Thunberg’s cycad status

Classified as Near Threatened (NT) on the IUCN Red List 2007 ⁽¹⁾, and listed on Appendix II of CITES ⁽³⁾.

Thunberg’s cycad threats

These attractive, ancient plants dominated Jurassic landscapes, but most cycad species are now rare and are threatened by over-collecting ^{(5) (8)}. Like other cycads, Thunberg’s cycad is a popular garden plant, and there is a particular demand for large specimens. Due to it being a slow-growing species, this has led to the indiscriminate removal of plants from the wild ⁽⁴⁾. In addition, there has been a minor reduction in suitable habitat for Thunberg’s cycad. While this is not believed to be a major threat at present, cycad populations are typically very localised and do not disperse large distances, therefore habitat destruction could rapidly affect an entire population and so is a potentially great threat ⁽⁸⁾.

Thunberg’s cycad conservation

The listing of Thunberg’s cycad on Appendix II of the Convention on International Trade in Endangered Species (CITES), means that any trade in this species should be carefully monitored ⁽³⁾. However, this measure does little to prevent illegal collection, which poses a significant threat to the species. Fortunately, many populations of Thunberg’s cycadoccur in protected areas, including Baviaanskloof Conservation Area, Groendal Wilderness Area, Longmore State Forest and the Addo Elephant Park ⁽⁴⁾, which may offer a degree of protection against illegal collection. In addition, cycad nurseries are making cultivated plants available for the horticultural trade ⁽⁴⁾, which will help lessen the demand for wild Thunberg’s cycads. Having survived since before the dinosaurs, hopefully such measures will allow this incredible cycad to survive the impact of humans.

Find out more

For further information on Thunberg’s cycad see:

• The Cycad Society of South Africa:
  www.cycadsociety.org
• PlantZAfrica:
  www.plantzafrica.com

Authentication

Glossary

Endemic

A species or taxonomic group that is only found in one particular country or geographic area.

Fynbos

The natural shrubland vegetation occurring in the southwestern and southern Cape of South Africa, holding the greatest diversity of plant species in the world. Fynbos is characterised by tall shrubs with large leaves, heath-like shrubs, wiry reed-like plants, and bulbous herbs.

References

1. IUCN Red List (September, 2007)
   http://www.iucnredlist.org
2. The Cycad Society of South Africa (November, 2007)
   http://www.cycadsociety.org/
3. CITES (November, 2007)
   http://www.cites.org
4. PlantZAfrica (November, 2007)
   http://www.plantzafrica.com/
5. Royal Botanic Gardens, Kew (November, 2007)
   http://www.kew.org/plants/cycads/index.html
6. The Gymnosperm Database (November, 2007)
   http://conifers.org/
7. Jolivet, P. (2005) Cycads and beetles: recent views on pollination. The Cycad Newsletter, 28: 3 - 7.
8. Donaldson, J.S. (2003) Cycads. Status Survey and Conservation Action Plan. IUCN/SSC Cycad Specialist Group, IUCN, Gland, Switzerland and Cambridge, UK.