Absinth wormwood
(Artemisia absinthium)

Description:
It is a herbaceous perennial plant, with a hard, woody rhizome. The stems are straight, growing to 0.8-1.2 m (rarely 1.5 m) tall, grooved, branched, and silvery-green.

The leaves are spirally arranged, greenish-grey above and white below, covered with silky silvery-white hairs, and bearing minute oil-producing glands; the basal leaves are up to 25 cm long, bipinnate to tripinnate with long petioles, with the cauline leaves (those on the stem) smaller, 5-10 cm long, less divided, and with short petioles; the uppermost leaves can be both simple and sessile (without a petiole).

Its flowers are pale yellow, tubular, and clustered in spherical bent-down heads (capitula), which are in turn clustered in leafy and branched panicles. Flowering is from early summer to early autumn; pollination is anemophilous. The fruit is a small achene; seed dispersal is by gravity.

It grows naturally on uncultivated, arid ground, on rocky slopes, and at the edge of footpaths and fields.

• Mechanical: Although it spreads rapidly on disturbed sites, it is easily controlled by herbicides and/or vigorous competition from grasses
• Biological: Absinth wormwood, which contains the sesquiterpene lactone absinthin,
  can be toxic to other plants in its vicinity.
• Herbicide: Picloram provides the most rapid and complete control of absinth wormwood, but dicamba, 2,4-D, and glyphosate are also effective.

For More Information:
Detailed information about absinth wormwood is available at the Washington State Noxious Weed Control Board Web Site.