The Artemesia genus consists of several Mugworts, Wormwoods, Southernwood and the spice Tarragon, with most being aromatic. Many are very similar to one another.
Not to be confused with : Woodworm, a 'worm' which bores holes in (usually dead) trees and wood.
Like Tansy (Tanacetum vulgare) it has discoidal flowers which are similarly aromatic (although not smelling of absinthe), yellow and consist solely of disc-florets - but they are much wider at 6-10mm across and the leaves are feathery and finely divided similar to those of Yarrow (which has much larger flowers that also have white petals and which is also aromatic, although that smells differently to both Wormwood and Tansy).
Easily mistaken for :
Sea Wormwood (Artemesia maritima) but that grows in drier saltmarshes, has narrower leaves and tubular flower heads that are only 1.5 - 3.5mm across (as opposed to 5mm across and discoidal for Wormwood) [a plant of similar name]
Some similarities to :
Field Wormwood (Artemesia campestris ssp. campestris) since that too has yellow florets which droop downwards but they are slightly smaller (at 3-4mm across) and the plant is not aromatic. It is found by roads and heathland and is much rarer than either Wormwood or
Sea Wormwood. The other sub-species is Dune Wormwood (Artemisia campestris ssp. maritima which is found on sand-dunes. Both these sub-species are a very rare RRR.
Slight resemblance to Ragweed (aka Annual Ragweed) (Ambrosia artemisiifolia) which also has downward-facing yellow discoidal flowers, but the flowering spike has a high-density of flowers which are not interspersed with leaves (or bracts). The leaves of Ragweed also look similar to those of Mugworts and Wormwoods, hence the specific epithet artemisiifolia.
Perennial Ragweed (Ambrosia pilostachya) has a similar slight resemblance to Wormwood.
Uniquely identifiable characteristics
Distinguishing Feature :
Wormwood is an archaophyte in the UK, having naturalised many centuries ago but is native to temperate regions of Europe and Asia and also to Northern Africa growing on waste ground, gravels pits, quarries, waysides, hedge-banks and other rough ground. Seed dispersal is gravity-fed. It has a very strong aromatic small (when young) with an odour of the infamous alcoholic drink absinthe. It is also used as flavouring for some other spirits and wines such as bitters, Vermouth and Pelinkovac.
ESSENTIAL OIL OF WORMWOOD
Wormwood is dried in air first before the essential oils are extracted, which amount to anywhere between 0.1% to 1.1$ of the total mass. About 107 compounds have been identified in the oil from plants grown in various countries around Europe (hence the huge variability in composition), representing 85% of the total oil. Therefore 15% of the oil had un-identified components. The principal constituents were found to be Sabinene (at anywhere between 0.9% to 30.1%), Myrcene (0.1% - 38.9%),
1,8-Cineole (aka Eucalyptol 0.1% - 18%),
Artemesia Ketone (0 - 14.9%), Linalool plus α-Thujone (1.1% - 10.9%), β-Thujone (1.1% - 64.6%%), trans-
EpoxyOcimene (0.1% - 59.7%), trans-Verbenol (0 - 11.7%), Carvone (0 - 18.5%), (E)-
Sabinyl Acetate (0 - 70.5%),
Curcumene (0 - 7.0%),
Neryl Butyrate (0.1% - 13.9%),
Neryl 2-MethylButyrate (0.1% - 13.9%),
Neryl 2-MethylButanoate (0.1% - 9.2%),
Neryl 3-MethylButanoate (0.4% - 7.3%), Chamazulene (0 - 6.6%). There were a great number of other more minor constituents that were identified amongst them Chrysanthenyl Acetate,
Aromadendrene (0 - 0.4%),
Bisabolol (0 - 7.5%) found in
German Chamomile (Matricaria recutita), Ledol (0 - 0.6%) which is a poisonous sesquiterpene found in the non-native
Bog Labrador Tea (Rhododendron groenlandicum) and two other Species of Rhododendron and which can cause cramp, paralysis and delirium.
The huge variation in concentration of the secondary metabolites not only depends upon where in the World the Wormwood was growing, but also on the growing conditions it has experienced - such as sunlight, water, temperature, and any other forms of stress that the plant may have experienced such as attempted invasion by parasites such as fungi or other organisms. Moreover, the time of year it was harvested, whether nascent, mid-season or near the end-of-season.
It is the Thujones in the oil which are the most toxic part if used for making Absinthe; they are neurotoxic and cause disturbances to the Central Nervous System which can lead to convulsions, kidney failure, epileptic seizures, long-lasting psychiatric disturbances and ultimately perhaps even death with a sufficiently large dose. Thus Wormwood used for Absinthe must have low levels of these Thujones, but that was not appreciated until fairly recently. Absinthe has been banned in several countries because of its toxicity, but it is now making a comeback providing that any thujones present are at a very low level. The Chamazulene also exhibits toxicity.
Aromadendrene is just one of a plethora (to be found in the list above) of aromatic sesquiterpenes to be found within Wormwood. It consists of a 5-membered ring fused to a 7-membered ring which is fused to a 3-membered cyclopropane. See also Aromadendranes
Another source of this huge variation in composition is due to the presence of a number of differing Chemotypes of Wormwood, where minor genetic or epigenetic changes in the plants DNA have a large effect in determining which types of secondary metabolites it produces whilst having little or no effect on the jizz, morphology or form of the plant. Nine or more such chemotypes have been identified in Wormwoods from around Eurasia, each producing a plethora of chemicals based upon at least nine differing chemical types. Three of the nine or more chemotypes are 'pure' types:
EpoxyCymenes chemotype, cis-Chrysanthenyl Acetate chemotype, and Thujone chemotype; the others are impure 'mixed' chemotypes such as the
Sabinyl Acetate + Myrcene chemotype. If Absinthe manufacturers made their concoction using Wormwood plants that do not belong to any Thujone-producing chemotype they would be well on their way to producing Absinthe with low levels of the toxic Thujone which is therefore legal to sell. But whether or not it contains poisonous quantities of any other sesquiterpene, most of which are toxic to some degree, is another matter...
SESQUITERPENE LACTONES and DIMERS
Santonin was used pharmaceutically as an anthelmintic - to treat parasitic worms, but has fallen out of favour in many countries for safer alternatives. It has structural similarities to Parthenolide which is found in Feverfew. Although present in Wormwood it was/is obtained at higher concentrations from the flowerheads of the non-native variety of
Sea Wormwood (Artemisia maritima) called Artemisia maritima var. stechmanniana.
Artabsin, which has similarities to Lactucin, is another sesquiterpene lactone contained in the volatile oil of Wormwood and is the monomer of Absinthin shown below.
Absinthin tastes extremely bitter and is responsible for the distinctive taste of the infamous alcoholic beverage called Absinthe.
Notice that Absinthin consists of two identical parts (one part shown in red), with an extra add-on, and is in fact the result of a dimerization process which takes place within the plant. Note that the end result, Absinthin, is not a true dimer because an extra out-of-plane bridge has been added (shown in blue). Before dimerization, the two individual units were Artabsin, shown above.
Artemisinin is one of a family of drugs used to treat Malaria which is caused by the parasitic organism Plasmodium falciparum and spread by some mosquitoes in tropical climates. It is obtained from
Sweet Wormwood (Artemisia annua), a non-native plant which yields the compound in higher quantities more reliably than does Wormwood itself. Artemisinin is a
sesquiterpene lactone - but one with an extra and highly unusual (in natural compounds)
peroxide bridge ( -O-O- ), which is believed responsible for the drugs potency against the malaria parasite. Use of this compound alone to treat malaria is discouraged because it seems to easily induce drug-resistance; it being far more effective to attack the malaria parasite with a cocktail of differing compounds at once. To this end a series of artificially produced analogues of Artemisinin have been produced synthetically, but the high cost of chemical synthesis of both artemisinin itself and of other similar intricate compounds is limiting its global use. Huge strides have been made in greatly reducing the occurrence of malaria in some parts of the World, but a great deal more effort must be expended to eliminate malaria from the World.
A genetically engineered yeast has been made which will synthesize
Artemisinic Acid which greatly simplifies the synthesis of Artemisinin and other Artemisinin derivatives, such as
Artelinic Acid and
Artemotil, all of which possess the active
peroxide bridge across an
Oxepane moiety (the fully-saturated 7-membered carbon ring possessing 6 carbon atoms and a heterocyclic oxygen atom). Other plant secondary metabolites with a peroxide bridge include Achillin found in Yarrow.
Although Artemesinin and other artemesinins can be administered alone, they are usually used with other dissimilar anti-malarial drugs to prevent recurrence of parasites if administered singly. They cannot be used prophylactically (to prevent infection) because their half-life within the body is short; only for treating malaria once caught. The World Health Authority recommends the administration of Artemisinin Combination Therapies (ACT), where Artemisinins are used in combination with dissimilar partner drugs possessing much longer half-lives, such as
Pyronaridine - all synthetic drugs and all of which contain one or more halogen atoms such as fluorine or chlorine which are very rare (chlorine) or virtually absent (fluorine) in biologically produced substances. But it is most important for those under treatment to take the full prescribed treatment rather than stopping when the symptoms subside; some remnants may linger.
Artemisinins are also effective against parasitic worms and can be used as an anthelmintic for Schistosomiasis, a tropical disease spread by freshwater snails which contaminate the water by releasing parasitic worms whereupon they bore into human flesh as folk (mainly children) play or wash in the parasitised rivers.
Artemisinin is also effective against a wide variety of cancers, and is a very effective treatment for leukaemia and colon cancer, less so for melanoma, breast, ovarian, prostate, central nervous system or renal cancers.