Artemisia afra – known as lengana, uMhlonyane, wilde als and African wormwood in South Africa – has been used as a traditional cure for flu-related illnesses such as colds, fever, coughs and headaches by generations of South Africans. 

This species, and others in the genus, are some of the oldest and best-known medicinal plants globally and are still used in South Africa by people of all cultures. Dried material (Fig. 1) for making herbal infusions as well as ready-to-drink tonics can be purchased from street vendors, traditional healers and large online commercial retailers alike.

International spotlight on lengana 

As the coronavirus pandemic gripped Africa earlier this year, lengana was thrust into the spotlight following claims by the Madagascan president that a herbal infusion based on a closely related species – Artemisia annua (mugwood, sweet wormwood), which has its origins in Asia – was a cure-all remedy and a preventative against Covid-19 infection.

Following these claims, many countries particularly in central and east Africa, imported the brew, marketed as Covid-Organics, for local and wide-scale distribution. However, at the same time the World Health Organization (WHO) and the African Centre for Disease Control (Africa CDC) cautioned that no clinical evidence existed in support of the herb as an effective cure or as a preventative against Covid-19.

Back in South Africa, many people turned to the locally occurring lengana, which grows in damp grasslands and forest margins throughout much of the country, in response to spiralling Covid-19 infections (Fig. 3). Before the pandemic, the plant was easily accessible from street vendors and various traditional markets, but the public’s reaction to the pandemic saw an increase in the harvesting and sale of Artemisia afra, particularly in Gauteng, Limpopo, Mpumalanga and KwaZulu-Natal, where increases in demand drove up both harvesting and pricing.

An article in the July edition of Business Insider SA (Ramalepe, 2020) indicated that the demand for Artemisia afra ‘had sky-rocketed’ and ‘prices had at least doubled’. At the beginning of 2020, the street price for three-quarters of a cup of dried lengana leaves (around 250 g) was in the region of R20–R40. In July the same quantity cost R100. At the time of writing this article, 250 g milled material retails for R750 on Takealot (online retailer). As an illustration of the quantities in which the plant is being traded, raw material can also be bought from street markets in ‘half-rubbish bags’ for R500.

Further pushing up prices are reports that lengana plants are, understandably, becoming harder to find as infection rates continue to rise. The elevated pricing is of concern – being unable to afford modern medicine dictates that an estimated 80% of people in developing countries still depend directly on wild-harvested products as medicine. Decreasing availability raises alarm around the sustainable use of Artemisia afra as a resource, although the species is not currently of conservation concern.

Like its counterpart from Madagascar, there is no scientific evidence supporting the plant’s efficacy in treating Covid-19. However, the species has been included along with other African plants in a programme funded by South Africa’s Ministry of Higher Education, Science and Innovation, researching the efficacy of plant-based products in treating Covid-19 symptoms.   

Can the ‘miracle herb’ withstand increased harvesting disturbance? 

The SAEON Ndlovu Node’s relationship with lengana predates the global coronavirus pandemic by 10 years. The species was first encountered in grasslands in Limpopo in permanent vegetation plots established to detect and monitor the response of this endangered vegetation type to local (fire, climate) and global (climate change) drivers of change (Fig. 5). The monitoring plots now lie within the more recently proclaimed Haenertsburg Nature Reserve; this area is unfenced and so the local plant diversity is still subjected to the further pressure of resource harvesting.

Use and the trading of medicinal plants have significant socioeconomic importance, and the harvest of wild plants is an increasingly recognised disturbance to plant populations (Fig. 4). The popularisation of lengana through 2020 provided the impetus to have a look back at our data for this species.

Artemisa afra is a woody, long-lived shrub (Fig. 2A) that we encountered only infrequently during three repeat surveys. Just 14 individuals were recorded from 90 monitoring plots in both the 2011/12 and 2015 surveys. However, of these, only five individuals were recovered in the 2019/20 survey that concluded in March 2020 (Fig. 6, left), just days before the National State of Disaster was declared in response to the Covid-19 pandemic. This marked loss of lengana individuals, which was most pronounced in bush-encroached areas experiencing periodic management fires, is likely the result of the extreme drought of 2015/16 coupled with an unplanned burn in the former year. The species is known to recover readily from frost and fire damage through coppice (Fig. 2B), but appears particularly drought sensitive. Despite average rainfall since 2017, no recruitment of lengana has been observed in the SAEON Ndlovu Node’s monitoring plots.

Fewer surviving individuals translates into fewer stems (Fig. 6, right), which is critical from a natural resource use perspective as these stems are the unit of harvest. It does not take much of a mental exercise to see that these few remaining plants and their reduced number of stems will not survive long in the race to provide lengana to a burgeoning market. And, with Covid-19 infections in South Africa currently showing a rapid increase, there is no indication that pressure on this resource is likely to alleviate any time soon.

A follow-up survey is planned for March 2021, which marks the end of the current growing season and one year since the start of the global pandemic. The question is, can lengana – the ‘miracle herb’, withstand increased harvesting disturbance at a time when populations are already debilitated by recent drought and inappropriate land management practices?

The use of natural resources is age-old; only knowledge on the effects of disturbance, which includes harvesting alongside more familiar global change characters such as climate and fire, can form the basis of informed and sustainable resource-utilisation practices.

Further reading

Business Insider article: https://www.businessinsider.co.za/life/atremisia-plant-and-price-increase-2020-7