The golden, orange and yellow flowers of T. oppositifolia make a stunning show in spring.
Tripteris oppositifolia is a dwarf shrub up to 1 m high. The leaves are semi-succulent, opposite, oblong, greyish green with smooth margins. The large flower heads are solitary (borne singly) and pedunculate (short-stalked). The involucral bracts are brown, divided, with appendages on bracts, uniform, in a single row. The yellow or orange ray florets are distinctly longer than the involucre. The disc florets are dark purple. The fruits develop from the ray florets. They are three-winged, hence the genus name, with three apical windows. Flowering time: May to October with the high peaks between August and September.
Tripteris oppositifolia is not currently included in the South African plant Red Data List of Golding (2002), and is quite common in the areas where it occurs naturally.
Distribution and habitat
The genus has ± 22 species in southern and tropical Africa, north to Egypt, the Arabian Peninsula and Jordan. There are 20 species in southern Africa that are widespread but absent in Swaziland and KwaZulu-Natal. Tripteris oppositifolia is found in Van Rhynsdorp, Namaqualand up to as far as Namibia. The soils and habitats listed on herbarium specimens include dry, sandy, rocky ground; well-drained, loamy clay soil; along the road; semi-desert and succulent karoo. Altitude ranges from 75 to 1 000 m.
Derivation of name and historical aspects
The generic name Tripteris is derived from the Greek words, tri meaning three, and pteris meaning wings. The species name oppositifolia means that the leaves are opposite. Originally this species was described as Calendula oppositifolia by William Aiton (1731-1793), a British gardener and botanist of the Royal Botanic Gardens at Kew (Aiton 1789). The name was changed to Osteospermum oppositifolia by Norlind (1960), a Swedish botanist, who was the curator of the Botanical Museum of Lund from 1950 to 1961. He was interested in taxonomy, morphology, phytogeography, cytology and ecology, especially of South African Compositae (Calenduleae) and the flora of Mongolia. In 1994, Nordenstam synonomized O. oppositifolia under Tripteris oppositifolia. He is a Swedish botanist, who was the curator of in Swedish Museum of Stockholm in 1969, and is interested in taxonomy and phytogeography of South African Compositae and Liliaceae.
Tripteris oppositifolia is pollinated by bees, wasps, butterflies and yellow spiders that match the flower heads exactly in colour. The fruits are winged, so are easily dispersed by wind. Plants in Namibia are more hairy compared to those found in Namaqualand. This may help reduce water loss and help them to survive in the dry conditions in the desert. This species is aromatic and palatable, especially when in flower.
Growing Tripteris oppositifolia
Sow seeds directly into prepared beds on a calm day when the wind will not blow them away. For best results, prepare the beds with compost and keep beds moist to trigger germination. They also grow very well in rocky, well-drained, sandy soil areas. As it is palatable to animals, farmers can plant it on farms as a type of backup fodder plant. For spring display grow Tripteris oppositifolia together with Didelta carnosa (seegousblom), Euryops pectinatus (gouemargrietjie), Euryops virgineus (river resin bush) and Pteronia incana (wild rosemary).
References and further reading
- Aiton, W. 1789. Diadelphia-Cryptogamia. Hortus Kewenis 3: 272.
- Golding, J.S. 2002. Southern African plant Red Data Lists. Southern African Botanical Diversity Network Report No.14.
- Joffe, P. 2003. Easy guide to indigenous shrubs. Briza Publications, Pretoria.
- Le Roux, A. 2005. Namaqualand. South African Wild Flower Guide 1. Botanical Society of South Africa, Cape Town.
- Nordenstam, B. 1994. New combinations in the tribe Calenduleae. Compositae Newsletter 25: 46.
- Norlindh, T. 1960. Subgenus Tripteris (Less.) T.Norl., section Trifenestrata T.Norl. Botaniska Notiser 113: 393-399.
- Stafleu, F.A. & Cowan, R.S. 1976. A selective guide to botanical publications and collections with dates, commentaries and types. Taxonomic Literature 1A-G, edn 2. Bohn, Scheltema & Holkema, Utrecht.
National Herbarium, Pretoria