Harpagophytum procumbens (Burch.) DC. ex Meisn.

Genus Naming and Origin

Harpagophytum (pronounced HAR-pə-GOF-it-əm), commonly known as devil's claw, and also called grapple plant and wood spider, is a genus of plants in the sesame family that is native to southern Africa.

The genus gets its common name devil's claw from the unusual hooked shape of its fruit.

Note that several North American species in the genus Proboscidea and some Pisonia species are also called devil's claw.

Folk Medicine Use

The tuberous roots of devil's claw are used in folk medicine to reduce pain.

Species Distribution

Harpagophytum procumbens is mainly found in eastern and southeastern Namibia, southern Botswana, and the Kalahari region of the Northern Cape, South Africa.

H. zeyheri occurs in northern Namibia (Ovamboland) and southern Angola.

Habitat Conditions

Harpagophytum procumbens grows in deep, sandy soils in areas with low annual rainfall between 150 and 300 mm per year.

Plant Growth Form

It is a perennial, tuberous plant that produces new creeping stems each year.

Above-ground stems sprout after the first rains, and die back during droughts or after frosts.

Tuber Structure

Stems grow from a long-lasting primary tuber; the harvested parts of the plant are secondary tubers that grow from the primary tuber at the end of fleshy roots.

Name Etymology

The plant gets both its scientific and common names from the hooked spines on its woody capsules.

Fruit and Seed Traits

Mature fruit opens slowly, so only 20 to 25% of a plant's seeds may come into contact with soil in a single year.

Seeds have a high level of dormancy, a low respiration rate, and can remain viable in the soil seed bank for more than 20 years.

Trade Sustainability Concerns

The sustainability of the international devil's claw trade has been a topic of concern for many years.

Range State Protection Policies

The governments of the three range countries where the plant grows—Namibia, Botswana, and South Africa—have created policies and regulations to protect the species, set sustainable harvest limits, and support continued livelihoods for harvesters.

CITES Listing Proposals

Proposals have been made at different times to list the species for protection under the Convention of International Trade in Endangered Species (CITES), but these proposals were withdrawn after the range states implemented sustainable trade management measures.

Ecological Research Overview

Multiple studies have investigated the biological and ecological needs of both harvested and unharvested devil's claw populations.

Early short-term studies in Botswana looked at the species' ecological requirements, while more recent work has surveyed the resource and studied sustainable harvesting methods.

Ecological Requirement Importance

Understanding the ecological requirements of a harvested species is necessary to manage harvest to maintain sustainability.

Socioeconomic Harvest Study

Stewart and Cole (2005) studied the complex economic, social, and cultural factors connected to devil's claw harvest.

2009 Population Study Design

Stewart (2009) assessed population structure, density, growth, mortality, and seed and fruit production in harvested and unharvested populations in the Kalahari savannas of South Africa.

Habitat Density Variation

Plant density and population structure differed significantly between overgrazed areas and grass-dominated areas, which suggests the variation may stem from competition for limited water and nutrients.

Harvest Mortality Findings

Experimental harvest via removal of secondary tubers did not cause significant mortality in any of the harvested size classes.

Harvest Growth Impacts

Harvest also did not impact overall growth, though medium-sized plants grew more over the study period in both harvested and unharvested populations.

Fruit Production Traits

Fruit production was highly variable, and mature fruits only developed under favorable conditions.

Harvest Resilience Findings

Under the conditions of this experimental harvest, the species appears resilient to harvest; harvested plants survived at the same rate as unharvested plants.

Research Data Gaps

However, because of the spatial variation in the species' habitat and the phenotypic plasticity of the plants themselves, more harvest data from large numbers of plants in actual harvested areas is needed to better understand the species' full life history.

Traditional Use Origin

Ethnobotanical use of devil's claw originated in southern Africa.

Botswana Cultural Significance

H. procumbens is one of the floral emblems of Botswana, where it is believed useful for treating a range of pain conditions.

Modern Herbal Uses

Preparations made from the plant or its extracts, including the compound harpagoside, are used as an anti-inflammatory herbal drug or dietary supplement in folk medicine and phytotherapy.

Clinical Efficacy Overview

There is no universally accepted clinical evidence of devil's claw's efficacy and bioavailability, but limited effects have been observed for treating lower back pain and osteoarthritis.

2016 Cochrane Review Findings

A 2016 Cochrane review of clinical research found that devil's claw appears to reduce low back pain more effectively than placebo, though the evidence was only of moderate quality at best.

Future Research Outlook

As of 2022, further research into the plant's effects on pain and inflammation is considered worthwhile.