Arctopus echinatus is an easily recognizable, flat-growing, spiny-leaved geophyte. It is an important South African medicinal plant with a long history of recorded use.

Description
Arctopus echinatus is a stemless, summer-deciduous perennial, up to 6 cm high and 60 cm in diameter. Roots relatively large, tuberous and exude a sticky resin when broken. Leaves large, simple, prostrate, ovate to rhomboidal in outline, with spiny margins and sharp recurved thorns between the leaf divisions. Plants either male or female. Male flowers cream and borne on short flower stalks. Female flowers greenish, stalkless, arranged in flower-like heads (pseudanthia) surrounded by four or five prominent spiny bracts. Fruit dry, brown and spiny.

Flowering time: May–July.

Conservation status
Least Concern (LC).

Distribution and habitat
Widespread throughout the winter rainfall region of South Africa, usually on seasonally moist sandy soils from Niewoudtville to the Cape Peninsula and eastwards to Port Alfred.

Derivation of name and historical aspects
The name Arctopus is derived from Greek, meaning ‘bear's foot', alluding to the broad, almost paw-shaped, simple leaves that lie flat on the ground and which are armed with large recurved thorns (‘claws'). The genus is endemic to the Greater Cape Floristic Region of South Africa and consists of three easily recognizable species, of which A. echinatus is the best known and most widespread (Magee et al. 2008).

Ecology
The genus Arctopus is an unusual member of the family Apiaceae, with each plant being either male or female (i.e. dioecious). Male and female plants are quite unmistakable with the males bearing umbels of small cream flowers and the females bearing greenish flowers enclosed by large spiny bracts to form a flower-like head (or pseudanthium). Pseudanthia are commonly found in other closely related and often ornamental genera, such as Alepidea, Astrantia and Eryngium. The shape, size and spinescence of these pseudanthium bracts are important diagnostic characters to distinguish between the three species (Magee et al. 2008). In Arctopus echinatus they are boat-shaped, with an acute spine-tipped apex and inflexed, overlapping spines along the margin. In the threatened A. dregei Sond. they are rolled inwards, with an obtuse spine-tipped apex and inflexed, spinescent hairs along the margin, while in A. monacanthus Carmich. ex Sond. they become very large and foliose, with an obtuse, spine-tipped apex and a usually entire margin. It is likely that the pseudanthium serves a protective function against herbivores, and it is also plausible that it may aid in the dispersal of the fruits by sticking to the fur or feet of animals. In A. monacanthus, however, the pseudanthium if far more brittle and breaks apart at maturity, so that each fruit is attached to a single large bract which may aid in wind dispersal.

Uses and cultural aspects
The roots of Arctopus echinatus have a long history of recorded medicinal use (Magee et al. 2007). The plants were held in high esteem as a ‘comfort to the sick', hence the Afrikaans vernacular name sieketroos (Pappe 1847, 1857). It is thought to have been adopted from the Khoi-San by the early Cape Dutch settlers (Pappe 1847, 1857), however no original Khoi-San name is retained today (Theodore 1972). It has also been recorded by the common names platdoring and pokkiesdoring, the latter suggesting a more specific connotation with its use against syphilis (Afr. pokkies). The virtue of a decoction of the root of A. echinatus has been expressed by several authors over the last two centuries but most notably the famous Swedish botanist and explorer Carl Thunberg (Smith 1966), and the assistant surgeon to the Forces, Dr James Barry (Theodore 1972). A decoction of the root has traditionally been taken orally for the treatment of syphilis, gonorrhoea, epilepsy, bladder ailments, glandular swellings, water retention, as a blood purifier and a general tonic (Watt & Breyer-Brandwijk 1962) and applied topically for the relief of inflammatory skin disorders, sores and ulcers. The resin from the roots is also recorded to be applied directly to treat ringworm, and the root chewed raw for tuberculosis as well as for numerous bladder ailments (Van Wyk & Gericke 2000). The biological activity has been ascribed to the presence of kaurene-type diterpenoids (Holzapfel et al. 1995; VanWyk et al. 1997) and phenolic acids (Olivier et al. 2008), similar to those found in another closely related medicinal plant, Alepidea amatymbica (ikhathazo).

Growing Arctopus echinatus

Information regarding the cultivation of A. echinatus is currently unavailable. Plants collected in the field have been maintained in cultivation and seem to continue growing even if only a fragment of the tuberous root is recovered. The plants should be kept in full sun, keeping them relatively moist during the cool winter months. They seem to be able to tolerate a period of waterlogging, however, a dry summer dormancy period is recommended. Although unlikely to be considered conventionally attractive, the broad bright green leaves and interesting flower-like heads could make it an appealing subject for a large pot.

References and further reading

• Holzapfel, C.W., Van Wyk, B.-E., De Castro, A., Marais, W. & Herbst, M. 1995. A chemotaxonomic survey of kaurene derivatives in the genus Alepidea (Apiaceae). Biochemical Systematics and Ecology 23: 799–803.
• Magee, A.R., Van Wyk, B.-E. & Van Vuuren, S.F. 2007. Ethnobotany and anti-microbial activity of sieketroos ( Arctopus species). South African Journal of Botany 73: 159–162.
• Magee, A.R., Van Wyk, B.-E., Tilney, P.M. & Van der Bank, M. 2008. A taxonomic revision of the South African endemic genus Arctopus (Saniculoideae, Apiaceae). Annals of the Missouri Botanical Garden 95: 475–490.
• Olivier, D.K., Van Wyk, B.-E. & Van Heerden, F.R. 2008. The chemotaxonomic and medicinal significance of phenolic acids in Arctopus and Alepidea (Apiaceae subfamily Saniculoideae). Biochemical Systematics and Ecology 36: 724–729.
• Pappe, L. 1847. A list of South African indigenous plants, used as remedies by the colonists of the Cape of Good Hope. Cape Town.
• Pappe, L. 1857. Florae Capensis Medicae Prodromus, vol. 2. Cape Town.
• Smith, C.A. 1966. Common names of South African plants. Memoirs of the Botanical Survey of South Africa No. 35.
• Theodore, J. 1972. Sieketroost: Dr James Barry's contribution to materia medica. South African Medical Journal 46: 1013–1016.
• Van Wyk, B.-E. & Gericke, N. 2000. People's plants: a guide to useful plants of southern Africa. Briza Publications, Pretoria.
• Van Wyk, B.-E., Van Oudtshoorn, B. & Gericke, N. 1997. Medicinal plants of South Africa. Briza Publications, Pretoria.
• Watt, J.M. & Breyer-Brandwijk, M.G. 1962. Themedicinal and poisonous plants of Southern and Eastern Africa, vol. 2. Livingstone, London.