After good winter rains, Euryops annuus transforms the barren plains of the Tanqua Karoo into fields of yellow, dainty flowers.
The plants of this genus are generally known as harpuisbos, but this species is not a typical Euryops, being an annual not a perennial.
Euryops annuus is an annual, hairless herb with fleshy leaves and bright yellow flower heads (inflorescences). The finely divided leaves are green and found in a basal tuft. The solitary flower heads are borne on long slender, erect peduncles (flowering stalks) up to 300 mm long. The peduncles are usually red to reddish brown. The flowers consist of yellow disc and ray florets, and a fully open flower head could be up to 45 mm in diameter. The involucre (calyx-like structure at the base of the inflorescence) is green and flat-based with the margins turned up vertically (cup-shaped). The flowering period is from May to September, only in favourable years. The seeds are grey, about 2 mm long and slimy when wet.
For a detailed description on the diagnostic features of the Asteraceae in terms of the flower structure, see the page on Asteraceae www.plantzafrica.com/plantab/asteraceae3.htm
Euryops annuus was originally thought to be rare. However, in 1941, after a year of unusually good winter rainfall, it formed vast patches of bright yellow and since then is considered to be locally very abundant.
Distribution and habitat
Euryops annuus is endemic to the Northern and Western Cape, South Africa. The distribution range is restricted to the Succulent Karoo Biome and it is found from the Calvinia District in the north to the vicinity of Prince Albert in the southeast. It prefers winter rain, a gentle slope of gravelly to sandy soil and full sun.
Derivation of name and historical aspects
Euryops annuus was described by R.H. Compton, who was a former director of the National Botanical Gardens of South Africa at Kirstenbosch (1919-1953). The name Euryops originates from the Greek words for large and eye/face, and refers to their large and showy flower heads. This species is the only annual in the genus Euryops, hence annuus as the species name (meaning annual).
The genus Euryops consists of 97 species, most of which are found in southern Africa, a few in tropical Africa and one species extending to the Arabian Peninsula and Socotra.
Euryops annuus is a pioneer plant which is found in vast numbers and dense concentrations in disturbed areas (old fields, ploughed areas and roadsides). The flowers are visited by bees and other pollinators. Tortoises, hares and small antelope graze the flowers, which are very nutritious. The seeds are eaten by small rodents and ants have been observed carrying the seeds into their nests. Since this small, annual plant can be abundant in early spring, it plays an important part in the food chain in these dry areas.
Uses and cultural aspects
The common name of the genus Euryops is harpuisbos, and is literally translated as resin bush. The name originates from the resin which is secreted from the stems and branches of most species in the genus. This resin was greatly esteemed by early inhabitants of the Cape Colony for its alleged medicinal properties. It is not known however, to what extent E. annuus contains resin, since it is an annual plant. The name kora is the local name used by people in the Tanqua Karoo.
Growing Euryops annuus
Euryops annuus has huge horticultural potential as a plant for rockeries and water-wise gardens in the winter rainfall area. Being small delicate plants, they only show their full glory when sown in large quantities to form dense showy expanses.
Euryops annuus, an ephemeral, has a short growing season, which is determined by the prevailing climatic conditions. The winter rains trigger seed germination and the plant comes into flower in a relatively short time, since it has to produce seeds before the onset of the hot, dry summer months. In cultivation and with extended watering, these plants will probably have longer growing seasons.
These plants could easily be grown from seed, but no information is available about any successful attempts in their germination and growing requirements.
References and further reading :
- 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.
- Leistner, O.A. (ed.). 2000. Seed plants of southern Africa : families and genera. Strelitzia 10. National Botanical Institute, Pretoria.
- Nordenstam, B. 1968. The genus Euryops. Part 1. Taxonomy. Opera Botanica 20: 138-142.
- Smith, C.A. 1966. Common names of South African plants. Memoirs of the Botanical Survey of South Africa No. 35.
- Watt, J.M. & Breyer-Brandwijk, M.G. 1962. The medicinal and poisonous plants of southern and eastern Africa, edn 2. Livingstone, London.
Beate Hölscher & Hester Steyn