Encephalartos trispinosus

(Hook.) R.A.Dyer

Family
: Zamiaceae
Common name : Bushman`s River cycad

Encephalartos trispinosus

This cycad responds well to cultivation when positioned in a sunny situation which is well drained. This species is not tall growing, suckers freely and forms large, attractive, grey-leaved clumps. It is hardy, withstands frost and does not require a great deal of water.

Description
Encephalartos trispinosus developes stems up to 1 x 0.25-0.3 m, which are branched from the base and not necessarily upright but tend to lean over. A mature plant can develop 4-6 stems with a number of suckers emerging at the base of the plant. Although cycads are considered to be slow growing, some species grow faster than others. E. trispinosus is, however, one of the slower growing species and like all of the other species, lives to a great age, provided that the plant grows in ideal conditions and is treated in the correct manner. The colour of the leaves is generally grey and they vary in size and shades of grey depending on which population they originate from. The leaves, 0.75-1.25 m long, are recurved and twist towards the tip. The leaflets consist of 3 lobes with a spine borne at each point.

Male coneThe cones of this species are bright yellow. One male cone is produced per stem, occasionally two. The cones are 250-350 x 70-80 mm. Female plants produce only one cone per stem and the cones are 400-500 x 180-200 mm . The scales are deeply wrinkled. The colour of the seeds ranges from pale red to orange. The cones emerge in midsummer. (January-December in South Africa ). Male cones are harvested in the autumn (April) and pollination of the female cones takes place in April-May.

Distribution
Encephalartos trispinosus is endemic to South Africa and occurs in the valleys of the Bushman`s and Great Fish Rivers in the districts of Bathurst, Alexandria and Albany of the Eastern Cape. The species is fairly common. The plants grow amongst rocks in full sun and also in shady situations with scrub vegetation. The climate is hot in summer and cold in winter with regular frost. The rainfall varies between 600-725 mm a year which occurs mainly in the summer.

Plant in habitat near Grahamstown

Derivation of name and historical aspects
Leaflets showing spinesThe species name trispinosus refers to the three spined lobes of the leaflets. This species was considered to be a variant of Encephalartos horridus or E. lehmannii until Dr R.A. Dyer reclassified it in 1965.

Ecology
Not a great deal is known about the pollination of cycads, however, it is assumed that they are wind pollinated and at the time of pollen dispersal there is much insect activity. Insects could also be responsible for pollination.

Uses and cultural aspects
Encephalartos trispinosus is an excellent garden subject in hot, dry climates and areas which experience frost. The plants do not require a great deal of water once established. Sunny situations, rockeries and desert gardens are ideal situations for this species. The living collection of E. trispinosus at Kirstenbosch is used for education, display and conservation by making seed and young plants available to botanic gardens and cycad enthusiasts.

Clump at Kirstenbosch

Growing Encephalartos trispinosus

This species can be used as an accent plant in rockeries, lawns and as a container plant. Ideal companion plants are low-growing aloes such as Aloe arborescens, Carpobrotus and Arctotis.

This species is slow growing but does well in cultivation provided that it is well drained and is exposed to full sun. Cycads require regular feeding. A thick layer of well-matured compost spread around the plant in autumn improves the condition of the soil and benefits the plants. An annual application of a well-balanced mixture of fertilizers applied in the spring is essential to maintain healthy cycads. A balanced inorganic fertilizer mixed with bonemeal and an organic fertilizer added is ideal.

The main pests which you can encounter when growing cycads are scale, mealybugs and snout beetle. The scale and mealybugs occur on the underside of the leaves and can be eliminated by applying a systemic insecticide. The snout beetles which destroy the seeds are nocturnal and can be eliminated by applying a contact insecticide. New leaves of cycads can also be damaged as they appear by a tiny mite. To avoid this damage, spray the new emerging leaves with a contact insecticide every two weeks. Regular spraying while new leaves are emerging will eventually eliminate the mite.

Propagation of Encephalartos trispinosus can be achieved by sowing seed or by removing well-matured suckers from the mother plant. To produce true to type seed it is necessary to hand-pollinate the female cone with pollen harvested from a male cone of the same species. Germination ranges from 30-40% on average. The seed is sown in spring on a bed of clean coarse sand which has bottom heat of 25-28º C. Within two months the seed germinates, producing a radicle followed by the leaves and 10 months later the seedlings are large enough to be removed and potted into 3 litre plastic sleeves, using a well-drained growing medium. The seedlings are watered sparingly until established.

Propagation by division involves removing well-developed suckers of approximately 250 mm in diameter from the mother plant. Early spring is an ideal time when all leaves are removed from the sucker which is then carefully pulled away from the main stem. The sucker needs to be left for two weeks so that the wound can dry before planting in clean sand to encourage root development. Once well rooted, the sucker can be planted out in the open ground.

Legislation relating to growing /owning cycads in South Africa

References and further reading

  • Giddy, C. 1978. Cycads of South Africa. Purnell, Cape Town .
  • Goode, D.1989. Cycads of Africa. Struik. Cape Town .
  • Jones, D.L. 2002. Cycads of the world. Smithsonian Institution Press.

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Kirstenbosch NBG
May 2006

 

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This page forms part of the South African National Biodiversity Institute's plant information website www.plantzafrica.com


 

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