Encephalartos princeps R.A.Dyer
Common names: Kei cycad (Eng.); keibroodboom (Afr.); umguza, umphanga (Xho.)
SA Tree No: 12
Encephalartos princeps is a lovely blue-leaved cycad that responds well to full sun and tolerates any soil type, provided that the soil is well drained and aerated. It is a relatively slow grower, and is frost-hardy and drought-resistant. Like all cycad species, it prefers moderate watering.
Encephalartos princeps is a woody plant with about 10-15 aerial, erect stems that form a cluster, though the stems may sometimes recline or lie flat on the ground. The stems may develop to a height of up to 5 m and a diameter of 300-400 mm. The leaves are 120-200 mm long, straight but curving downwards at the apex. They are blue-green with a silvery bloom when still young, but darken slightly with age. The median leaflets attain a length of up to 120-150 mm and a width of 10-13 mm. The leaflets at the base are reduced in size, and have one or two spines at the most. Male and female plants bear 1-3 dull green cones per season per stem. The cones are produced in January, with the male cone shedding pollen during April-June, and the female cones starting to break up during October-December.
According to Raimondo et al. (2009), Encephalartos princeps is Vulnerable (VU), as the best available evidence indicates that it meets all five IUCN criteria for Vulnerable, and is therefore facing a high risk of extinction in the wild.
Distribution and habitat
As its common name suggests, the Kei cycad is endemic to South Africa and is restricted to the catchment area of the Great Kei River (Eastern Cape). The plants grow in riverine scrub between rocks and on doleritic cliffs. The annual rainfall in its distribution area ranges from 420-520 mm, with hot summers and cool winters.
Derivation of name and historical aspects
In 1965 Encephalartos princeps was identified as a new species, separate from E. lehmannii, by Robert Allen Dyer. The specific name is derived from the Latin word meaning 'first', as Dyer believed that the species actually had a longer history than its ally E. lehmannii.
The male and female cones produce powerful odours in the early morning or evening to attract weevils. When the weevils move between the sexes, they inadvertently transfer the pollen from the male cones to the receptive ovules of the female cones.
The fleshy outer covering layer of the seeds of cycad is attractive to a range of animals such as birds, rodents and bats. Therefore, with some luck, the seeds are discarded some distance away from the parent plant to a hospitable environment in which they are likely to germinate.
Cycads can be used as decorative or focal point plants in the garden and can also be very effective as grouped plantings.
In ancient times, indigenous people used to make bread from cycad stem. However, one needs to note that most parts of cycads are toxic. All or most cycad seeds are poisonous, but not the pith inside the stems.
Growing Encephalartos princeps
Encephalartos princeps survives well in full sun, and is easily propagated from seeds and suckers (the young plants that grow around the main stem). The seeds should be collected, cleaned and stored in a brown paper bag for six months or more, at 10-15 ºC, to allow the embryo to fully develop. The seeds are cleaned to ensure that all the flesh is removed since it may contain germination inhibitors and could promote the growth of fungi. The flesh is scraped away with a knife but protective gloves should be worn during the cleaning operation to prevent contact with the slow-acting poisons in the flesh. If the flesh is hard and dry it helps to soak them in water for a day or two before cleaning. Even if the seeds have been cleaned, it is a good idea to soak them for a few days before planting them, preferably with daily changes of water. When the seeds are placed in water, the viable ones will sink and non-viable will float. To germinate the seeds, place the cleaned seeds on their sides half buried on washed sand or potting mix, and keep at 28 ºC. It is necessary to keep the medium moist, but not too wet, for as long as it takes for germination to take place. As soon as the radicles of the sprouted kernels are 10-20 mm long, these germinating kernels can be planted singly in bags containing potting soil or some other suitable medium. Alternatively one can wait until the seedlings develop one or two leaves before transplanting them individually into bags. Because cycad seedlings form long tap roots, it is advisable to use tall narrow perforated black plastic bags with a diameter of about 12 cm and a length of 24 cm for their initial establishment. Place the seedlings under shade for the first few years of growth and development. Initially the seedlings must be watered daily with a fine spray. As their roots elongate, after about a month the frequency of watering should be decreased to once a week. The seedlings can be transplanted into the garden when they are 3-5 years old.
When preparing to propagate from suckers, one must use a clean sharp knife or sharp spade to remove the sucker from the mother plant. The wound should then be treated with a fungicide and dried for about a week before planting into a sterile medium.
Cycads are ideal for a low maintenance garden as they require a minimum of water and are undemanding in their soil and environmental needs.
Pests that are troublesome to cycads are scale insects, beetles and chewing insects. Scale insects cause great damage to cycad leaves by sucking the sap from them. Most scale insects can be controlled with regular and frequent applications of horticultural soluble oil such as white oil. Beetles seriously damage cycad plants by attacking the emerging young leaves. Control can be effected by application of contact or systemic insecticide, or one of the bacterial preparations available.
- Barkhuizen, B. P. 1975. The cycad garden of UNISA. UNISA Press, Pretoria.
- Giddy, C. 1974. Cycads of South Africa. Struik, Cape Town.
- Grobbelaar, N. 2002. Cycads of Southern Africa. Author, Pretoria.
- Raimondo, D., Von Staden, L., Foden, W., Victor, J.E., Helme, N.A., Turner, R.C., Kamundi, D.A. & Manyama, P.A. (eds). 2009. Strelitzia 25. South African National Biodiversity Institute, Pretoria.
Pretoria National Herbarium
Plant Type: Tree
SA Distribution: Eastern Cape
Soil type: Loam
Flowering season: Early Summer
Aspect: Full Sun
Gardening skill: Easy