ERYTHRINA ZEYHERI, A MAGNIFICENT PLANT FOR LARGE CONTAINERS.
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 Much of the Erythrina zeyheri habitat in western Mpumalanga has been destroyed and fragmented by coal mining as indicated in this photograph. |
 Erythrina zeyheri is often associated with the headwaters of various rivers in western Mpumalanga. Unfragmented habitat such as this is now very rare. The scarce salmon pink flowered E. zeyheri are visible in the foreground and the more typical flame orange flowered plants in the background. |
 An Erythrina seed in the process of germinating in Penrock Specialist Flora Nursery. Fresh seed germinates very quickly and the deep tap root rapidly penetrates the soil and develops the initial elongated caudex. |
SUMMARY.
Few Erythrina species have caudexes. One of them that does is Erythrina zeyheri which has magnificent flame orange, dark orange red or salmon pink flowers. Salmon pink flowered plants are currently unavailable in cultivation but occur naturally in a small area of western Mpumalanga.
An overview is given in the newsletter of plants in their natural habitat and a detailed discussion is provided of methods for displaying the plants to their best effect in large terracotta pots.
Seeds of this species are available through Penrock Seeds and Plants are supplied by Penrock Plants. Johann and Leigh Nieuwoudt of Simply Indigenous Nursery also supply plants. These details follow at the end of the newsletter.
NEWSLETTER.
South African Erythrinas are mostly trees and shrubs. Two species in South Africa Erythrina acanthocarpa and Erythrina zeyheri have very large caudexes. In the case of E. zeyheri, the leaves and stems die back to ground level in the winter months sprouting again in spring, September and October.
E. zeyheri is found mainly in the grassland interior of eastern South Africa mostly in the provinces of Gauteng, Kwazulu Natal, Mpumalanga and the extreme eastern section of the North West Province. The Erythrina habitat in all these provinces has been fragmented and reduced by agriculture, commercial timber plantations, industrialisation, urbanisation and mine dumps. In former times the species used to be well represented in parts of Gauteng, Kwazulu Natal and the western parts of Mpumalanga. In western Mpumalanga the plants were often found in extensive scattered colonies in undulating grassland around the headwaters of various rivers. This habitat is completely fragmented these days by coal mining, urbanisation and maize fields.
THE GROWTH CYCLE.
E. zeyheri grows mostly in the early summer months flowering at the beginning of the rainy season. At this time the grasslands are brown and sere after the winter drought. The conspicuous blooms, which emerge well before the leaves are fully developed, are visible from afar.
It is likely that a range of insects pollinate the flowers and honey bees, various wasps and beetles have been seen visiting the flowers and collecting pollen.
Most pollinators, particularly honey bees are active from 10H00 until 15H30 on calm days. Far fewer pollinators are able to visit the flowers during windy weather. Pollination is usually most successful in the large scattered colonies of plants and least so where the Erythrinas exist in small patches of grassland near monocultures of maize or areas that are invaded by annual and perennial exotic plants.
Pollination is extremely variable from one year to the next. This curious phenomenon is not yet understood since even in years when numerous pollinators do visit the flowers little seed is set. Seeds take about 12 weeks to develop and mature to the stage where the ripe beans split open in sunny weather. This usually occurs during the first two weeks of February. A great deal of seed, almost the whole crop in some years, is destroyed by what appear to be Lepidopterous larvae.
Dry summer weather is required for the seeds to be liberated and distributed. If February is a wet month many seeds germinate in the partially opened beans where they shrivel and dry out when sunny weather returns. Seeds that lodge in suitable places germinate quickly and a caudex has already developed by the end of the rainy season in April. These caudexes are sufficiently well established to survive the dry winter until the first early summer rains break, the following October or November.
The Erythrina flowers are usually a magnificent flame orange. They may also be an orange crimson. Plants with buff and salmon pink coloured flowers appear to be very rare and confined to a small area of south western Mpumalanga. These plants occur together with those in the majority which have flame orange or orange crimson flowers.
THE CULTIVATION AND PROPAGATION OF ERYTHRINA ZEYHERI.
E. zeyheri is readily grown from seed sown in large deep containers. Seeds should be sown just under the surface of the soil or else with their upper surfaces exposed. They are best spaced about 5 cms apart. Seeds should be kept continually moist after sowing, whilst they are germinating and for the duration of the summer whilst the young plants are growing. They should not be watered from the time the leaves wither and yellow in late autumn until the beginning of the following spring.
The young caudexes develop quickly for the first few years but later take a long time to fill out and broaden. After 4 – 5 years they are ready for transplanting into large containers. The plants look particularly ornamental with the tops of their caudexes exposed amongst rock artistically placed in large terracotta containers.
The tubers may be planted in gardens or rockeries at the beginning of their third growing season. Alternatively seeds may be sown in situ where the plants are to be grown. The seeds and seedlings are best covered with netting for the first growing season, to protect them from birds.
E. zeyheri requires a sunny, well ventilated position to grow well. Care needs to be taken to make sure that the plants are only occasionally watered during the winter resting period.
PLANTS AND SEEDS.
Seeds are available through Penrock Seeds and plants via Penrock Plants and Simply Indigenous Nursery. Simply Indigenous Nursery is situated near the south western perimeter of Hartebeestpoort Dam in South Africa’s North West Province. The contact person is:
Leigh Nieuwoudt leigh@simplyindigenous.co.za or telephone 012 207-1077.
Photographs by Connall Oosterbroek