This is a small cycad with an unbranched, subterranean stem which rarely forms suckers. It is a frost-hardy species that grows best in light shade.
A small cycad with a subterranean stem of about 30 cm in height and 25 cm in diameter. It is normally a solitary plant which only branches when it is injured.
Leaves are about 1 to 2 m long, glossy bright green, straight, covered with a silky layer of hair when young. The median leaflets are 10 to 20 cm long and 1 to 1.5 cm broad, with one or two teeth on one or both margins. The leaflets decrease in size towards the base, but not to prickles, leaving the lower 15 to 20 cm of the leaf stalk bare to the base.
Male and female plants produce up to 4 cones which remain green at maturity. Male cones are narrowly cylindrical, 20 to 30 cm long and 8–10 cm in diameter. Pollen shedding takes place during May–September. Female cones are broadly cylindrical, 25 to 30 cm long and 12 to 15 cm in diameter. The female cones disintegrate spontaneously during September–December. Seeds are bright red; seed kernels are unique among the South African cycad species in that their surface is covered with small knobs.
Encephalartos striatus is often confused with E. villosus and even more often with E. cerinus.
The existence of the species in the wild is not particularly endangered, and it is not listed in the Red list.
Distribution and habitat
The species is restricted to the valley of the Umbeluzi River, both in Swaziland and Mozambique. It grows in sparse to dense, deciduous low forests, under hot and dry conditions in low scrub. The annual rainfall of the region varies from 625 to 750 mm and occurs mainly in summer. The species is a relatively slow grower. It grows best in light shade and is frost hardy.
Derivation of name and historical aspects
The epithet striatus, marked with longitudinal lines, refers to the leaflets and the epithet of the synonym umbeluziensis refers to the place where the species occurs, namely the Umbeluzi River.
Encephalartos species are pollinated by insects and wind in the wild, but it is advisable to apply hand pollination in the garden for better results. Cycad cones release a distinctive odour at maturity to attract insects for pollination purposes.
The fleshy outer covering layer of the seeds is desirable food to a range of animals such as monkeys, birds, rodents and bats. Therefore, with any luck, the seeds are discarded some distance away from the parent plant in a hospitable environment in which they are likely to germinate.
Uses and cultural aspects
Cycads can be used as attractive decorative or focal point plants in gardens and can also be very effective as grouped plantings with some succulents.
Growing Encephalartos striatus
It is easily propagated from seeds, but seedlings, at the one-leaf stage, are susceptible to the fungal disease “damping off” which kills the seedling's single leaf at ground level. The seeds should be collected, cleaned and stored in a brown paper bag at 10–15ºC for six months or more, 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 can also 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 present in the flesh. If the flesh is hard and dry, it helps to soak the seeds 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, preferably with daily changes of water, before planting them. When the seeds are placed in water, the viable ones will sink and the non-viable ones will float.
To germinate the seeds, place the cleaned seeds on their sides half buried on washed sand or potting mix, and keep at about 28ºC. 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 radicals of the sprouted kernels are 10–20 mm long, they 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 about 24 x12 cm in size 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. After about a month, as their roots elongate, the frequency of watering should be decreased to once a week. The seedlings can be transplanted in the garden when they are 3–5 years old. Cycads are ideal for a low maintenance garden, as they require a minimum of water and are undemanding in their soil and environmental needs.
Everyone in possession of cycads must have a permit. Please contact your provincial Nature Conservation authority for details.
Pests 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 kept by application of contact or systemic insecticides, or one of the bacterial preparations available.
References and further reading
- Barkhuizen, B. P. 1975. The cycad garden of UNISA. UNISA Press, Pretoria.
- Giddy, C. 1974. Cycads of South Africa . Struik, Cape Town.
- Jones, D.L. 1993. Cycads of the world : Ancient plants in today's landscape. Reed, New South Wales.
- Raimondo, D., Von Staden, L., Foden, W., Victor, J.E., Helme, N.A., Turner, R.C., Kamundi, D.A. & Manyama, P.A. (eds). 2009. Red List of South African plants 2009. Strelitzia 25. South African National Biodiversity Institute, Pretoria.
William Khutso Sepheka
Pretoria National Herbarium