Artemisia is notorious as a harmful drug and poisonous plant.  While some of this reputation may be justified, it is not all quite what it is written up to be.  There are some forms of Artemisia that contain as much as 50% harmful ketones by way of thujone.  This depends on the species and the growing of the plant.  Just the same, even in milder varieties its potentially hazardous chemotypes are generally considered much too potent in an essential oil form and is best left alone, although some essential oils are available, generally in the safer varieties, but not always, so it is bet to be aware.

Artemesia anua is used in perfumery.

Artemisia pallens or davana is available as an essential oil (see davana)

Artemesia dracunculus is better known as tarragon and is also available.

Avaiable, but which must be used with great caution and only by professional practitioners is Artemisia vulgaris, aka mugwort or moxa, commonly used in Chinese mediine as buring moxa or moxabustion in acupuncture.