The African genus Harpagophytum is a small one with only two species and three subspecies and consists of tuberous rooted perennial herbs with deciduous stems. The majority of taxa formerly included in Harpagophytum are now in the shrubby Madagascan genus Uncarina.

The common names for Harpagophytum species are "Devil's Claw" and "Grapple Plant" in reference to the spiny fruit. (The common name "Devil's Claw" is also applied to species in the genus Proboscidea in the New World plant family Martyniaceae.) The generic name is derived from the Greek: Harpage meaning a hook for seizing and Phyton meaning a plant.

The range of Harpagophytum is entirely within 15ºS and 30ºS and does not extend southward into the cape of South Africa.

The genus Harpagophytum has its closest affinities with Pterodiscus and Uncarina. Species in the African genus Pterodiscus are rather similar vegetatively but are easily distinguished by the fruit often having prominent wings and are never spinescent. The Madagascan genus Uncarina has spinescent fruit but unlike Harpagophytum, the plants are shrubby and the hooked spines are arranged in a star-like pattern on long stalks rather than being along elongate margins of the fruit.

The cut dried tubers of Harpagophytum procumbens are widely used as an herb and is packaged as an herbal remedy. The tubers contain the Iridoid glycosides harpagide, harpagoside and procumbide that are claimed to have anti-inflammatory and anti-rheumatic properties. However, controlled clinical studies have shown the herb to be ineffective with little or no actual therapeutic value. Furthermore, the herb lacks the anti-inflammatory properties possessed by all recognized anti-arthritic drugs of the nonsteroidal, anti-inflammatory analgesic type. (See Baghdikian et al. (1997) for more information.)

KEY TO THE SPECIES AND SUBSPECIES
(based on Ihlenfeldt & Hartmann (1970) and Ihlenfeldt (1988))
(translated from the original German by Maddy Lehmann and Alain Buffel.)

The genus Harpagophytum (Burch.) DC. ex Meissn. is divided into two species and five subspecies, for which we give the following key:

1. Fruit with 50-60 seeds in four rows on the placenta, spinescent arms longer than the width of the capsule………………..Harpagophytum procumbens (Burchell) DC. ex Meissner, 2

- Fruit with 20-30 seeds in two rows on the placenta, with entire margins or spinescent arms, both not longer than the width of the capsule…..Harpagophytum zeyheri Decaisne, 3

2. Leaf elongated, three-lobed or ovate and deeply crenate; fruit usually with three spinescent arms in each row, the longest approximately twice as long as the width of the capsule; flowers pale yellow or with pale yellow throat and purple lobes; 2-4 extrafloral nectaries per flower.

Harpagophytum procumbens (Burchell) DC. ex Meissner ssp. transvaalense Ihlenfeldt & H.Hartmann (1970)
Transvaal, north of the Soutpansberg, south of Zimbabwe.

- Leaf elongate or round, five-lobed; fruit usually with 4 spinescent arms in each row, longest spinecent arms twice to five times as long as the width of the capsule; flowers with yellow throat and purple lobes or with entirely purple corolla; two extrafloral nectaries.

Harpagophytum procumbens (Burchell) DC. ex Meissner ssp. procumbens
Botswana, Namibia north to 19 degrees Latitude.

3. Leaf ovate, margin entire to crenate; fruit with broad spinescent arms, length of spinescent arms not as wide as the capsule; flower 60 mm long, throat pale yellow, lobes purple; 2, rarely 4 extrafloral nectaries.

Harpagophytum zeyheri Decaisne ssp. sublobatum (Engler) Ihlenfeldt & H.Hartmann (1970)
Southern Angola, northern Namibia (to 19 degrees latitude), Western Zambia and Zimbabwe, upper reaches of the Zambezi River.

- Leaf lobed, at least some of the leaves during one season….4

4. Leaf deeply seven-lobed, spread strongly reduced; fruit triangular or lanceolate, stout, margin often reaching ¾ of the capsule width; 2-4 extrafloral nectaries on one flower; flower with yellow throat and purple lobes.

Harpagophytum zeyheri Decaisne ssp. schijffii Ihlenfeldt & H.Hartmann (1970)
Transvaal, one population in the northern part of the Kruger National Park.

- Leaf oval or three-lobed, often both forms on one plant; fruit with entire margins or short spinescent arms usually reaching the capsule width; 3-4 extrafloral nectaries; flower pale yellow or with yellow throat and purple lobes, rarely with entirely purple corolla.

Harpagophytum zeyheri Decaisne ssp. zeyheri
Transvaal, south of the Soutpansberg to the northern slopes of the Magaliesberg, Kruger National Park except in the far north.

LIST OF SPECIES

Harpagophytum De Candolle ex Meissner, Pl. Vasc. Gen. 2: 206 (1840)
syn. Uncaria Burchell, Trav. Int. S. Afr. 1: 536 (1822) not Schreber (1789)

Harpagophytum procumbens (Burchell) De Candolle ex Meissner, Pl. Vasc. Gen. 2: 206 (1840)
syn. Uncaria procumbens Burchell, Trav. Int. S. Afr. 1: 536 (1822)
Harpagophytum burchellii Decaisne, Rev. Bot. 1: 516 (1845)

Harpagophytum procumbens ssp. transvaalense Ihlenfeldt & Hartmann, Mitt. Staatsinst. Allg. Bot. Hamburg 13: 57 (1970)

Harpagophytum zeyheri Decaisne, Ann. Sci. Nat. (ser. 5) 3: 329 (1865)
syn. Harpagophytum peglerae Stapf in Bolus, Trans. S. Afr. Phil. Soc. 16: 398 (1906)

Harpagophytum zeyheri ssp. schijffii Ihlenfeldt & Hartmann, Mitt. Staatsinst. Allg. Bot. Hamburg 13: 58 (1970)

Harpagophytum zeyheri ssp. sublobatum (Engler) Ihlenfeldt & Hartmann, Mitt. Staatsinst. Allg. Bot. Hamburg 13: 58 (1970)
syn. Harpagophytum procumbens fa. sublobatum Engler in Baum, Kunene-Sambesi-Exped. 370 (1903)
Harpagophytum procumbens var. sublobatum (Engler) Stapf in T.Dyer, Fl. Trop. Afr. 4 (2): 548 (1906)

EXCLUDED NAMES

Harpagophytum subgenus Uncarina Baillion, Bull. Mens. Soc. Linn. Paris 1 (84): 668 (1889)
= Uncarina (Baillion) Stapf in Engler & Prantl, Naturl. Pflanzenfam. 4, 3b: 261 (1895)

Harpagophytum abbreviatum Baillion, Bull. Mens. Soc. Linn. Paris 1 (84): 670 (1889)
= Uncarina abbreviata (Baillion) Ihlenfeldt & Straka, Zeitschr. Bot. 50 (2): 158 (1962)

Harpagophytum dimidatum Baillion, Bull. Mens. Soc. Linn. Paris 1 (84): 669 (1889)
= Uncarina grandidieri (Baillion) Ihlenfeldt & Straka, Zeitschr. Bot. 50 (2): 157 (1962) (syn. Uncarina dimidiata (Baillion) Ihlenfeldt & Straka, Zeitschr. Bot. 50 (2): 158 (1962))

Harpagophytum grandidieri Baillion, Bull. Mens. Soc. Linn. Paris 1 (84): 669 (1889)
= Uncarina grandidieri (Baillion) Ihlenfeldt & Straka, Zeitschr. Bot. 50 (2): 157 (1962)

Harpagophytum leptocarpum Decaisne, Ann. Sc., Nat. Ser. 5 (3): 329 (1865)
= Uncarina leptocarpa (Decaisne) Ihlenfeldt & Straka, Zeitschr. Bot. 50 (2): 157 (1962)

Harpagophytum peltata Baker, Bot. Journ. Linn. Soc. 25: 341 (1890)
= Uncarina peltata (Baker) Stapf in Engler & Prantl, Naturl. Pflanzenfam. 4, 3b: 261(1895)

Harpagophytum pinnatifidum Engler, Bot. Jahrb. 10: 255, pl. 7 (1889)
= Pterodiscus speciosus J.D. Hooker, Curtis's Bot. Mag. 70: t. 4117 (1844)

REFERENCES

Baghdikian, B.; Lanhers, M.C.; Fleurentin, J.; Ollivier, E.; Maillard, C.; Balansard, G. & Mortier, F. (1997) AN ANALYTICAL STUDY, ANTI-INFLAMMATORY AND ANALGESIC EFFECTS OF HARPAGOPHYTUM PROCUMBENS AND HARPAGOPHYTUM ZEYHERI. Planta Medica 63 (2): 171-176.

Humbert, H. (1962) LES PEDALIACEES DE MADAGASCAR. Adansonia (ser. 2) 2 (2): 200-215, 3 pl.

Humbert, H. (1971) FLORE DE MADAGASCAR ET DES COMORES; FAMILLE PEDALIACEES 179e: 5-46, 13 figs. Museum National D'Histore Naturelle.

Ihlenfeldt, H.D. (1988) PEDALIACEAE in Launert, E. (ed.), Flora Zambesiaca 8 (3): 86-113, tab. 19-28.

Ihlenfeldt, H.D. & Hartmann, H. (1970) DEI GATTUNG HARPAGOPHYTUM (BURCH.) DC EX MEISSN. (MONOGRAPHIE DER AFRIKANISCHEN PEDALIACAEA II). Mitt. Staatsinst. Allg. Bot. Hamburg 13: 15-69, 12 abb., 1 taf., 3 karte.

Ihlenfeldt, H. & Straka, H. (1962) UBER DIE MORPHOLOGIE UND ENTWICKLUNGSGESCHICHTE DER FRUCHTE VON UNCARINA (BAILL.) STAPF (PEDALIACEAE). Zeitschrift fur Botanik 50 (2): 154-168, illus.

Rowley, G.D. (1987) CAUDICIFORM & PACHYCAUL SUCCULENTS. Strawberry Press.

Verdoorn, I.C. (1982) HARPAGOPHYTUM ZEYHERI. Flowering Plants of Africa 47 (1/2): Plate 1853.

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