Encephalartos paucidentatus

Stapf & Burtt Davy

Family
: Zamiaceae
Common name : Barberton cycad

Graceful cycad

The graceful crown of glossy dark green leaves, vigorous growth and strong stem of Encephalartos paucidentatus makes this one of the most striking of all cycads. As it is regarded as one of the most handsome species for cultivation, wild plants are unfortunately often illegally harvested.

Description
The stems of Encephalartos paucidentatus are either upright or procumbent and reach a height of 6 m with a diameter of 0.4-0.6 m. Occasionally they branch from the base. The dark, glossy green leaves are 1.5 to 2.5 m. New leaves are covered with a dense layer of brownish hairs which gradually disappear as the leaves mature. The leaf stalks are straight and yellow with the leaf crown being graceful and spreading. It is a forest species growing in semi-shade on rocky slopes. It is one of the faster growing species of cycad and under ideal conditions survives for many generations. The male plants produce up to 5 tall, slender, yellow cones, 400-600 x 120-150 mm, covered with brown hairs. They are supported by a 100 mm peduncle (stem). The pollen is released in early winter. Female plants produce 1-5 golden cones, 350-500 x 200-250 mm, supported by a short, sturdy peduncle.

Leaves

Status
In its natural habitat, Encephalartos paucidentatus has been considerably reduced and can now be regarded as an endangered species. All South African cycads are Cites listed plants.

Distribution and Habitat
This species occurs in the mountains of eastern Mpumalanga in a restricted area near Barberton as well as in the adjacent mountains in the Piggs Peak District of northwestern Swaziland . Plants occur at an altitude of up to 1 800 m with a rainfall of 1 250-1 500 mm a year. Conditions are cool and moist with plants occurring in low forest on steep and rocky slopes. Ideal conditions for the cultivation of the Barberton cycad are light shade and ample moisture in a frost-free area.

Derivation of name and historical aspects
The specific name refers to the Latin paucus which means few, and dentatus meaning toothed, in reference to the few teeth which appear on the leaflets of the specimens studied when this species was described. There has been confusion regarding the three sheets in the National Herbarium: Dr R.A. Dyer (1965) came to the conclusion that it was likely that George Thorncroft of Barberton and Reverend Rogers were responsible for the discovery of the Barberton cycad as they were instrumental in sending a specimen to The Royal Botanic Gardens, Kew and alerting the botanists to its existence. At the time, Thorncroft was in regular correspondence with the botanists Burtt Davy and Pole Evans.

Ecology
All cycads as far as we know are wind and insect pollinated. When cycads cone, the presence and activity of snout beetles increases dramatically. It is therefore assumed that they act as a pollinating agent.

Uses and cultural aspects
The Barberton cycad is very much sought after and is one of the most striking cycads in a garden provided it is given sufficient space to develop. The spread of the leaves of a mature plant is approximately 5 m.

Growing at Kirstenbosch

Growing Encephalartos paucidentatus

Encephalartos paucidentatus is a shade-loving species but can also be grown in full sun. This species develops to its full potential in light shade, moist conditions, good drainage in a frost-free situation, with space to grow. This species is one of the faster growing cycads. Once the stem has attained its maximum diameter the stem height, under ideal conditions, increases by 30-50 mm a year. The spread of its leaves can extend to 5 m and a mature plant can grow to a height of 6 m. When planting a young plant, it is important to consider all the above factors because once established, E. paucidentatus does not like to be moved. Cynthia Giddy (1978) suggests that as many roots as possible must be retained when moving a plant as they are difficult to re-establish. Grown in full sun, this species develops into a most attractive specimen plant but the leaves tend to be slightly shorter than when grown in shade.

In shade, Clivia, Crinum, Scadoxus multiflorus subsp. Katharinae, Plectranthus, Veltheimia and Asparagus make ideal companion plants for Encephalartos paucidentatus.

Cycads require regular watering and feeding to maintain a healthy plant. A 50 mm thick layer of mulch using well-matured compost applied in the autumn helps to improve the soil and benefits the cycads. In early spring, apply two generous handfuls per plant of a mixture of bone meal, organic fertilizer and a balanced inorganic fertilizer. High pressure irrigation systems which produce a strong jet of water are to be avoided as it will destroy the leaves as well as the stem of the plant.

The main pests which you can encounter on Encephalartos paucidentatus are scale, mealybugs, caterpillars, midges and snout beetles. Spray with a contact insecticide. Snout beetles destroy cycad seed and the scale and mealybugs occur on the underside of the leaves. New leaves can be damaged as they appear by a tiny gall midge: apply a contact insecticide every two weeks to the crown as the leaves emerge.

Propagation of Encephalartos paucidentatus can be achieved by sowing seed or removing well-developed suckers from the mother plant. To produce true to type seed, it is necessary to hand-pollinate the female cone with pollen harvested from the male cone of the same species. 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 leaves. Within 10 months the seedlings are removed and potted into a 3 litre plastic sleeve containing 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 eased away from the main stem. The sucker needs to be left for a week to dry off the wound before planting in clean sand to encourage root development. Once well rooted, the sucker can be planted out in the open ground.

References and further reading

  • Donaldson, J. & Winter, J. 1998. Grow cycads. Kirstenbosch Gardening Series. National Botanical Institute, Cape Town.
  • Giddy, C. 1978. Cycads of South Africa. Purnell, Cape Town.
  • Goode, D.1989. Cycads of Africa. Struik, Cape Town.
  • Osborne, R. 1991. Encephalartos paucidentatus. Encephalartos 27: 3-9.

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John Winter
Kirstenbosch Botanic Garden
July 2006

 

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