Karoo cycad (Encephalartos lehmannii)
|Size||Stem height: up to 2 m (2)|
Stem diameter: up to 50 cm (2)
Leaf length: 1 – 1.5 m (2)
Classified as Near Threatened (NT) on the IUCN Red List (1) and listed on Appendix I of CITES (3).
The Karoo cycad is one of around 300 living representatives of a plant group, the cycads, which flourished over 150 million years ago alongside the dinosaurs (4) (5). This squat, low-growing species commonly forms clumps with two or more stems branching from the same base (2) (6) (7). Although woody in appearance, the stems are mostly comprised of soft, pithy storage tissue protected by a solid layer of old leaf bases (6) (8). Topping each stem is a crown of long leaves, each comprised of numerous well-spaced, bluish-green or silver leaflets on either side of a central stem (6) (8). The reproductive organs of cycads take the form of cones, similar in appearance to those of a conifer (5), but in the Karoo cycad each stem produces just a singe cone (2). As with all cycads, the male and female cones of this species, both of which are bluish-green (7), are borne on separate plants (8).
The Karoo cycad is endemic to the Eastern Cape Province, South Africa (1) (2) (6).
Described as the hardiest and most drought resistant of the South African cycad species, the Karoo cycad occurs in semi-arid, low succulent shrubland, subject to very hot summers and cold winters (2) (6) (7). Although rainfall is concentrated during the summer months, it is erratic and the region is prone to prolonged droughts (2) (7).
Cycads are long-lived, slow growing plants that always occur as individual male or female plants (6) (8). There is no way of determining the sex of a cycad until it begins to produce its first cone (8). 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) (8) (9). To attract pollinators, male and female cones produce powerful odours, usually in the early morning or evening (8). 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 (8) (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).
While the Karoo cycad was once fairly abundant throughout its range, its numbers have declined dramatically as a result of the growing popularity of this species amongst collectors (7) (8). With the majority of plants in areas close to roads and towns removed, most Karoo cycads are now only found on higher ground in relatively inaccessible terrain (7). Other negative pressures on this species include domestic goats, which damage the leafy crowns, and porcupines, which eat the stem bases in times of drought. Furthermore, there is a weevil species that parasitizes the cones of female Karoo cycads, severely affecting its rate of regeneration (8).
Although the Karoo cycad is listed on Appendix I of the Convention on International in Endangered Species (CITES), which permits trade in this species only under exceptional circumstances, it is not found in any nature reserves (2) (3) (8). If this does not change and the remaining viable populations continue to be illegally exploited by collectors, the Karoo cycad faces the very real threat of extinction in the wild (3).
For further information on the Karoo cycad and conservation of cycads in South Africa see:
- The Cycad Society of South Africa:
- South African National Biodiversity Institute:
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- 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
- Parasitize: parasitism is an interaction between species in which one organism derives its food from, and lives in or on, another living organism at the host’s expense.
- 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
IUCN Red List (April, 2008)
The Cycad Society of South Africa (November, 2008)
CITES (November, 2008)
- Donaldson, J.S. (2003) Cycads, status survey and conservation action plan. IUCN/SSC-Cycad Specialist Group. IUCN, Gland, Switzerland.
Royal Botanic Gardens, Kew (November, 2008)
The Cycad Pages (November, 2008)
PlantZAfrica (November, 2008)
- Whitelock, L.M. (2002) The Cycads. Timber Press, Portland, Oregon.
- Jolivet, P. (2005) Cycads and beetles: recent views on pollination. The Cycad Newsletter, 28: 3 - 7.
- 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.