Artemisia annua (sweet wormwood)
Top of an Artemisia annua flowering plant (Photo: Lin Yu-Lin)
Artemisia annua L.
sweet wormwood, sweet Annie, annual wormwood (English); qing hao (meaning ‘blue-green’ artemisia) (Chinese)
Widespread, widely naturalised, and often abundant; not of conservation concern, but not yet evaluated according to IUCN Red List criteria.
Hillsides, edges of forests and wasteland.
Medicinal, important anti-malarial, essential oil used in cosmetics, cultivated as an ornamental in Indonesia.
About this species
Sweet wormwood is an annual, aromatic herb from Asia, and has been used in China to treat fevers for more than 2,000 years. The genus Artemisia belongs to the Compositae (daisy and sunflower family) and includes well-known plants used in medicine, perfumery and the food and drink industry, such as A. dracunculus (tarragon), A. absinthium (absinthe) and A. vulgaris (mugwort). The ancient Greeks thought wormwood (A. absinthium) was a remedy for sea-dragon bites.
Sweet wormwood is the source of the Traditional Chinese Medicine (TCM) ‘Qing Hao’, which has been used for more than 2,000 years to alleviate fevers. In TCM it is often prescribed in combination with other herbs to treat (in addition to fevers) jaundice, headache, dizziness and nosebleeds. Scientific research into the anti-malarial activity of sweet wormwood began in the early 1970s in response to the increasing resistance to established anti-malarial drugs of the protozoan parasites which cause malaria (Plasmodium species). The chemical artemisinin, which occurs naturally in the leaves of sweet wormwood, is a potent anti-malarial agent, and can kill the most deadly malarial parasite, Plasmodium falciparum (it is selectively toxic to the asexual erythrocyte stage of the parasites). Artemisinin extracted from sweet wormwood has become extremely important in treating malaria, since resistance to many other anti-malarials has become widespread.
Artemisinin content varies widely depending on the provenance of the plants from which it is extracted. Many research programmes are underway focusing on the selection and cloning of high artemisinin-yielding chemotypes (plants that may be indistinguishable from one another in appearance but are nevertheless unique in their chemical composition). In addition, various chemically engineered artemisinin derivatives have now been developed based on the naturally occurring chemical.
Sweet wormwood is also valued for its essential oil which is sometimes used in cosmetics and perfumes. The oil has been reported to have anti-microbial activity. Sweet wormwood is also grown locally as an ornamental in Java, Indonesia.