All species are wind-pollinated and usually produce large amounts of pollen. These plants may be the most significant cause of pollinosis after ragweeds and the grasses.
Artemisias are usually aromatic and bitter annual or perennial herbs or shrubs. Artemisia species are common in western states with up to 11 species present in the Rocky Mountains. The alternate, lacy, lance-shaped, or oblong leaves vary greatly in size among species. Plant heights vary among species from 1 to 10 feet tall. Flowers are small, yellow or white, with nodding or erect in spikes. Artemisia species flower during midsummer and autumn months, which can vary depending on latitude and elevation. One species, sagebrush, flowers from July to late September with allergenic pollen that can cause pollinosis in western US. Another species, wormwood, is common in central states and flowers in late summer and autumn.
Pollen grains of Artemisia are prolate spheroidal to subspheroidal and 3-colporate. The colpi are long and the sexine is thickened equatorially and thinner at the poles with short spinules (0.6um long) interspersed with granules.
The shaded areas on the map indicates where the genus has been observed in the United States.
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