Artemisia sp.

Sagebrush, Mugwort, Wormwood

By: H. Wayne Shew, Ph.D.
NAB Certified Pollen Counter
AAAC Collection Station—Birmingham, Alabama

The genus Artemisia is a large, diverse genus of plants having between 200 and 400 species. Its name is derived from the Greek goddess Artemis (the namesake of the Greek queens Artemisia I and II). The genus is a member of the largest and certainly one of the most diverse plant families, the family Asteraceae. The majority of species are hardy herbs, but some members are classified as shrubs. Species in this genus are known to have powerful chemical components (essential oils) that give the plants strong aromas and bitter tastes. These essential oils are chemically composed of terpenes and sesquiterpene lactones. Presence of these chemical constituents discourage herbivory and thus gives these species some selective advantage. Most species grow in temperate habitats and are present in both northern and southern hemispheres. They are most commonly found in dry or semiarid regions.

Mugwort

A. vulgaris, Mugwort (http://identifythatplant.com/wp-content/uploads/2011/12/Mugwort13-1024x909.jpg)

The most familiar members of this genus are: A. tridentata (sagebrush), A. vulgaris (mugwort), A. absinthium (wormwood), and A. dracunculus (tarragon). The plants have alternately arranged leaves that are simple, but with distinct lobes. Some species have leaves covered with white hairs, some have the underside of the leaves appearing white while the upper surfaces are green, and some species have leaves which are green on upper and lower surfaces. The flowers of these plants are small and are wind-pollinated, hence, the reason I am writing this blog. Artemisia is one of the genera that we look for in our daily pollen counts and one which we report to the National Allergy Bureau. In fact, this group of plants may rank just behind ragweed and grasses as the plants most often causing pollinosis. Also, if you are allergic to ragweed or other Asteraceae species, then you may be allergic to this Asteraceae species as well.

Some uses of species of Artemisia include:
A. dracunculus (tarragon) is a culinary herb and is often used in French cuisine.
A. vulgaris (mugwort) has been used to repel various insects including midges, fleas, and moths. It has also been used in the brewing of beer, mugwort beer, which supposedly acts as a remedy against hangovers.
A. absinthium (wormwood) is used in the production of absinthe, a potent, highly alcoholic beverage (90-148 proof) that contains green anise and sweet fennel in addition to wormwood. Vermouth is a wine originally flavored with wormwood but now with other aromatic herbs.
A. stelleriana is one of the plants bearing the common name Dusty Miller and it and some other species of Artemisia are grown as ornamental plants.

Some medicinal uses of species of Artemisia include:
1. Artemisinin and derivatives of it which are obtained from A. annua, and are now part of standard treatments worldwide for malaria.
2. Santonin obtained from A. cina and other Old World species of Artemisia is used as an antihelminthic drug.
3. The species A. argyi is used in traditional Chinese medicine.
4. The species A. austriaca has been shown to have beneficial effects in reducing withdrawal symptoms for individuals seeking to end morphine addiction.
5. The species A. capillaris has compounds that act as potent sedative/hypnotic drugs.

Artemisia genus, single grain

Artemisia genus, single grain (Above figure from: http://www.pollenlibrary.com/Genus/Artemisia/ )

Artemisia genus, multiple grains

Artemisia genus, multiple grains (Above figure from: http://www.pollenlibrary.com/Genus/Artemisia/ )

The pollen grains of Artemisia are 19-25µ, spheroidal in shape, and elongated along the polar axis (prolate). The grains have three openings called colpi with a bulging hyaline pore at the equatorial region of each colpus (technically the grains are called tricolporate). Because of these bulging pores these grains resemble oak pollen when seen from a polar perspective. The pollen grains of Artemisia have a very thick exine which causes them to appear very different from the pollen of other Asteraceae plants; particularly noticeable when seen in polar view. (see figures below) The pollen grains have very short spines (0.6µ long) interspersed with granules.