Knowltonia capensis (L.) Huth
Common names: blistering leaves (Eng.); brandblare, katjiedrieblaar (Afr.)
This is a very handsome plant with unusual flowers resembling green buttercups, that does well in shady situations.
A slow-growing, stemless perennial herb between 300 and 500 mm tall. Flowers consist of coloured sepals, there are no petals (this distinguishes it from Ranunculus). It has a slender flowering stem 450 mm long, with a compound umbel (i.e. several flower stalks originating from one point on the main flower stem) of creamy-green flowers, from June to September. These are followed by fruits which are small, fleshy berries in dense clusters, green turning black when ripe. A short rhizome with fleshy roots is present. The tooth-edged, basal leaves are distinctive, being tough, coarse and leathery in texture, they are usually trifoliately compound, i.e. divided into three distinct leaflets with the middle leaflet slightly larger then the two on the side.
Distribution and habitat
Grows at the forest margins, is common in coastal bush and forested kloofs. This plant is most common in the East London area from where it extends eastwards to the midlands of Natal and westwards to the Cape Peninsula. As it has a rhizome, it will most probably be able to tolerate frost quite well, and it can cope with both high and low rainfall due to its wide distribution range.
Derivation of name and historical aspects
Named in honour of T. Knowlton, an English botanist and director of the formerly famous Botanic Garden at Eltham. Capensis means coming from the Cape.
Ranunculaceae, also known as the buttercup family, comprise about 50 genera and 800 species that occur worldwide. Seven genera and about 17 species are found in southern Africa.
Other indigenous members of this family worth mentioning are Clematis brachiata (traveller's joy), a lovely climber with scented, cream-coloured flowers followed by clusters of seeds with persistant feathery 'tails' and Anemone tenuifolia, a perennial that blooms most profusely after veld fires, making a splendid show of white or pink on the higher Cape mountains.
Bruised leaves cause blistering of the skin, hence the common name. This plant is used as an old Cape remedy for lumbago and rheumatism, leaves are also used to make an infusion for use in treating stomach complaints. Decoctions of the roots mixed with Pelargonium roots, have also been used to treat colds and influenza. Members if the Ranunculus family contain a bitter-tasting glycoside, ranunculin. When fresh roots and leaves are eaten or bruised, this compound is enzymatically converted to a highly toxic oil with an acrid taste that causes the blistering. Smoke from burning leaves or the fumes from crushed leaves may be inhaled for headaches. Leaf poultices of these plants are widely used in traditional medicine to treat wounds, external cancers and rheumatism. Roots of Knowltonia may be directly applied to alleviate toothache.
Growing Knowltonia capensis
The unusual green flowers make this plant a feature in any garden. Best planted in massed clumps they will tolerate a variety of garden conditions, as they are hardy and very tolerant. Dry to moist soil, not too wet, deep to light shade, rich to nutrient-poor soil, this plant does not demand much from a gardener and rewards amply. The plant, however, enjoys receiving regular water and compost.
There are not many plants that are as well suited to growing and flowering in the shade or under trees as Knowltonia. They do not grow tall, so use them in front of a bed or around the base of a tree(s), planted alone or with any other shade-loving species. When planting in combination with other plants, look at using those with similar water requirements as Knowltonia is quite water-wise. It will also do well in pots.
It is easily grown from seed, and large plants can be divided after flowering.
- MORIARTY, A 1982. Outeniqua, Tsitsikamma, eastern Little Karoo. South African Wildflower Guide 2, Botanical Society of South Africa, Cape Town.
- JACKSON, W.P.U. 1977. Wild flowers of Table Mountain. Howard Timmins, Cape Town.
- LEISTNER, O.A. (ed.). 2000. Seed plants of southern Africa: families and genera. Strelitzia 10. National Botanical Institute, Pretoria.
- POOLEY, E. 1998. A field guide to the wild flowers of KwaZulu-Natal and the eastern region. Natal Flora Publications Trust, Durban.
- VAN WYK, B-E. & GERICKE, N. 2000. Peoples plants. A guide to useful plants of South Africa. Briza Publications, Pretoria.
Kirstenbosch National Botanical Garden
Plant Type: Perennial
SA Distribution: Eastern Cape, Western Cape
Flowering season: Spring, Winter
Flower colour: Green, Cream
Gardening skill: Average