This attractive shrub is grown mainly for its fine foliage. Along with several other species in this genus, it is overlooked as a garden plant. Very little research has been done in terms of propagation and it is hoped that the information provided here will be useful to plant lovers, amateur botanists and gardeners and that it will stimulate interest and encourage cultivation of a wider range of these plants.
Searsia discolor is a tall, robust, erect shrublet, up to 1 m high, arising from a large woody rootstock, bark smooth, the many stems densely covered with hairs. Leaves are grey-green above, covered with thin hairs and greyish or white-felted below, margins curled back; three leaflets sessile (without stalks), forming a compound leaf. The contrast between the upper and lower surface is very attractive and the leaves are even more attractive when the upper surface turns red in autumn.
The genus Searsia consists of herbs, shrublets, shrubs and trees. This shrub has typical Searsia flowers borne between October and May. The flowers are small, greenish to yellowish, sometimes whitish flowers, normally in clusters between the top leaves and sometimes protrude above the leaves. As in other Searsia spp., male and female flowers occur on separate trees and only females form fruits which are drupes. The grassveld currant has round, smooth and yellowish brown fruit. Searsia discolor is sometimes confused with broad-leaved forms of Searsia rosmarinifolia.
Most of the populations recorded are in conservation areas and not threatened. These populations also show growth. Not much information is recorded on its status in other areas, but it is widespread in the eastern half of South Africa .
Distribution and Habitat
Occurs in rocky grassland in the eastern Free State, Gauteng, Limpopo, KwaZulu-Natal, the Eastern Cape, Lesotho and Swaziland . This plant can tolerate some frost if it is grown between other plants as it is normally protected by the grasses in its natural habitat. This plant grows well in moist areas, semi-shade and direct sun. It can tolerate some drought. It occurs from sea level to 2 000 m.
Derivation of name and historical aspects
Searsia was named after Paul B. Sears (1891-1990) who was head of the Yale School of Botany and dentata is derived from Latin meaning deeply toothed. The Latin name discolor means two different colours which refers to the leaf coloration.
This genus is easily confused with the genus Allophylus, but can be distinguished by the resinous smell of crushed leaves, brownish lenticels on the branches and the resin exuding from the base of the leaf stalk. Members of Allophylus usually have round, red fruits, a character that distinguishes them from species of Searsia.
Most of the species grown in southern Africa, belonging to the genus Rhus, have been placed in Searsia. In southern Africa there are about 111 species of Searsia. Searsia discolor is endemic to South Africa.
In nature, most species of Searsia occur in arid areas and they therefore have a deep root system. They can grow in almost any kind of soil and are of much importance in nature because of the berries they produce which are a source of food to birds, certain wild animals and humans.
This plant is equally at home in grassy and rocky areas, which makes it adaptable to veld fires. Fires promote new growth. Ants are the seed dispersal agents and bees and small beetles are the main pollinators of this plant.
Uses and cultural aspects
Insects such as bees, ants, beetles and flies are attracted to this plant at flowering stage. Birds like the fruit. The fruits are edible and are believed to cause constipation; some cultures burn it during their rituals for better yield of crops. The branches and leaves are believed to be poisonous and can cause death if swallowed, but not the fruit.
This plant can best be used best in the garden as in groups. During flowering time it will attract the eye when planted in the bright light areas.
Growing Searsia discolor
In the absence of veld fires, this small shrublet needs a pruning to stimulate the growth of fresh leaves. It is effective when planted in masses in the garden, as a border or background plant; or it could be grown as a pot plant in a large container. It requires a sunny or semi-shady spot and reasonable moisture to perform at its best, but will survive short droughts which seem to enhance autumn coloration.. Mulching will help to maintain moisture. It is happy to grow surrounded by groundcovers in place of the grass it would encounter in the wild.
This species can be propagated successfully from seed. The following propagation method has been tested successfully: to speed up the germination of seed, it is recommended that seeds be sown in trays and put on subsurface heating beds and/or under a mist spray and kept at a constant temperature of 20-25 ° C. Hygiene is one of the most important factors that should be taken into consideration when raising plants from seed to avoid fungal diseases. The standard propagation medium to be used for Searsia species in general is the following: 1 part sand, 1 part compost/leaf mould and 1 part topsoil. The three components should be mixed well to form a loose, well-drained medium. No artificial fertilizers should be added.
Sun-dried seeds have proved to germinate quickly. Sow the seeds immediately after they have been dried. Prepare the seed trays by putting a drainage layer at the bottom. Fill the trays with the medium and firm it down with a seed press, but do not force the soil down as it then becomes compact, hampering the drainage. The medium should be moist. Spread the seeds lightly over the prepared sowing mixture and firm them down lightly.
Dust the seed with fine ashes of wood (grey powder) before covering them, to keep insects away. Do not over-water the seed trays to avoid rotting. Place the seed tray in a cool, shady, well-ventilated place. The seed tray should not be in full sun during the germinating stage. Germination time varies from 10 to 60 days depending on the species, seed treatment and depth of the seeds. They should be covered at 1½ times their thickness.
Seeds that have geminated should be watered daily, but the seedlings can be affected by damp-off when over-watered. The best time to sow seeds of thi s species is just after winter, in early spring. Transplant seedlings as they develop to the 3rd or 4th leaf stage. Moisten and then shake the tray to loosen the medium and prevent damage to the root system. Remove the seedlings with a dibber. The transplanting soil mixture should consist of the following: 3 parts red soil, 1 part compost and 1 part sand.
The seedlings respond very well to artificial fertilizer such as 3:1:5 and 2:3:2. Young plants need lots of water but once they are established, they do not need much; they are therefore a good subject for water-wise gardening. In general they do well with a surface dressing of a thick layer of leaf mould (natural organic matter).
Aphids attack the leaves and scale insects damage the stems of the plants and they therefore have to be sprayed with Karba Spray and Oleum to prevent this infestation.
References and further reading
- Acocks, J.P.H. 1988. Veld types of South Africa , edn 3. Memoirs of the Botanical Survey of South Africa No. 57. Botanical Research Institute, Pretoria .
- Carr, J.D. 1994. The propagation and cultivation of indigenous trees and shrubs on theHighveld . Sandton Nature Conservation Society and the Tree Society of Southern Africa, Johannesburg .
- Coates Palgrave, K. 1981. Trees of southern Africa . Struik, Cape Town .
- Johnson, D., Johnson, S. & Nichols, G. 2002. Gardening with indigenous shrubs . Struik, Cape Town.
- Moffett, R.O. 1993. Flora of southern Africa , Vol. 19, Part 3, Fascicle 1. National Botanical Institute, Pretoria .
- Moffett, R.O. 2007. Name changes in the Old World Rhus and recognition of Searsia (Anacardiaceae). Bothalia 37(2):165-175
- Palmer, E. 1977. A field guide to the trees of southern Africa . Collins, London .
- Van Wyk, B. & Van Wyk, P. 1997. Field guide to trees of southern Africa . Struik, Cape Town .
- Venter, H.J.T. 1976. Trees and shrubs of the Orange Free State . De Villiers, Bloemfontein.
Mr. Mashudu Peter Gavhi
Free State National Botanical Garden