When walking along a stream or near a wetland on a warm day in spring or early summer, a strong sweet smell is sometimes the first indication that one of our largest ericas is in flower. Then you will notice a large bushy shrub or small tree with tiny white or yellowish flowers and grey branches standing out amongst the surrounding greenery. On closer examination you may recognize the flowers as those of the water heath, Erica caffra.
Erica caffra may grow as an upright bush or a small tree up to = 4.5 m high. The bark of the trunk, especially on old plants, is brown and deeply fissured, while that of younger trees and branches is grey. The branches are long and thin and carry many slender twigs. Leaves which may be deep green or grey and hairy and are arranged in groups of three along the twigs. They are 8-19 mm long and have the typical needle shape of most ericas, with margins that are rolled in towards the back of the leaf. The white, cream or yellowish flowers occur in groups of 2 or 3 in the axils of the leaves in a spike-like arrangement along the twigs. They are bell- or urn-shaped, about 5-7 mm long. Long-lasting, with a strong honey scent, they are pollinated by bees and later become a rusty brown. It is estimated that there are about 50 000 of the fine dust-like seeds in a single gram, and that about 30 would weigh as much as a single poppy seed.
Erica caffra is a very widespread species, always occurs in wet or damp places along streams and rivers and is often part of the riparian vegetation, where it gets some protection from fires. More widely distributed than most ericas, it occurs in the northwest from Van Rhynsdorp and the Cedarberg, all the way down to the Cape Peninsula in a broad band, then eastward to the Transkei and up into Lesotho, at altitudes from sea level to about 1 800 m. Tolerant of a fairly wide range of conditions as long as the soils remain damp, it is found where the rainfall ranges from fairly low to quite high and which may occur in winter, summer or all year round.
Derivation of name and historical aspects: The generic name Erica comes from the Greek word, ereike, which means to break. This was because it was thought that an infusion of certain heath plants would help break up kidney stones. The species name caffra is derived from the word kaffir, an Arabic word for an unbeliever, used by the early explorers for the indigenous people they found in the country. Erica caffra is one of about 760 species of Erica in South Africa (about 860 world-wide; Europe only has 21 species) and one of few that reaches tree status and that is highly scented. The presence of so many ericas in the fynbos is one of the components that make this veld type so special and have helped it to earn the status of one of the most important floral kingdoms on earth, the Cape Floral Kingdom. Erica is the largest genus in the South African flora and together with the Protea and Restio families, make the fynbos a very important biome. The other well-known genera belonging to the Erica family are rhododendrons, azaleas, cranberries, bilberries and blueberries.
The seeds are dispersed by the wind. Bees and possibly other small insects are the pollinators of Erica caffra. When the seed is mature, the capsule (fruit) dries out and four splits open, allowing the minute seeds to be blown about by the wind. The small, needle-shaped leaves are adapted to the harsh conditions that many ericas grow in by having few, if any, stomata on the upper surface of the leaf. The leaf edges curl inwards to protect the lower surface of the leaf, where there are stomata, thus helping to conserve moisture.
Uses and cultural aspects
The wood is regarded as useless because it shrinks and cracks as it dries, as can be seen from the little bowls in the photograph. Dead branches make good kindling. Although this is an Erica probably not much seen in any but the more specialized indigenous nurseries, it does have a place in a wet garden.
Growing Erica caffra
Erica caffra is an attractive plant when in flower but can look rather scruffy for the rest of the year. If one has a wet plot or needs to add fine texture to a streamside planting, then perhaps this would be a good choice. It grows in acidic, damp or even wet soils which are not stagnant. They must also not contain manure and must have low levels of phosphate. About 50 % of the soil must be humus for successful growing. As the seeds are extremely tiny, it would be good to mix them with a quantity of fine sand before sowing them on a finely sieved growing medium containing sandy loam and compost that is acidic and well drained.
Seeds may either be presoaked in aqueous smoke extract or smoke seed primer for 24 hours before sowing, or water the sown seed tray with these solutions. Water trays with a very fine rose, making sure that the evenly distributed seeds are not disturbed. Placing a sheet of glass over the seed tray helps maintain the conditions required for germination which takes place from one to two months after sowing. When the seedlings are about 10 mm tall, move them out into the open under light shade. They can be pricked out and potted up when they are 20-50 mm high and again placed in light shade. Once established, move them out into the sun for growing on, but keep damp throughout the process.
References and further reading
- Brown, N. & Duncan, G. 2006. Grow fynbos plants. Kirstenbosch Gardening Series. South African National Biodiversity Institute, Cape Town.
- Coates Palgrave, K. 1983. Trees of southern Africa. Struik, Cape Town.
- Germishuizen, G., Meyer, N.L., Steenkamp, Y. & Keith, M. (eds). 2006. A checklist of South African plants. Southern African Botanical Diversity Network Report No. 41. SABONET, Pretoria.
- Goldblatt, P. & Manning, J. 2000. Cape plants. A conspectus of the Cape flora of South Africa. Strelitzia 9. National Botanical Institute of South Africa and Missouri Botanical Garden Press, USA.
- Jackson, W.P.U. 1977. Wild flowers of Table Mountain. Timmins, Cape Town.
- Leistner, O.A. (ed.). 2000. Seed plants of southern Africa: families and genera. Strelitzia 10. National Botanical Institute, Pretoria.
- Palmer, E. & Pitman, N. 1972. Trees of southern Africa, vol. 3. Balkema, Cape Town.
- Powrie, F. 1988. Grow South African plants. Kirstenbosch Gardening Series. National Botanical Institute.
- Smith, C.A. 1966. Common names of South African plants. Memoirs of the Botanical Survey of South Africa No. 35.
- Von Breitenbach, F. 1986. National list of indigenous trees. Dendrological Foundation.
Harold Porter National Botanical Garden