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Dyer's Woad (Brassicaceae
(=Cruciferae), the mustard family
 BACKGROUND: Dyer's woad was introduced into North America from Europe,
 probably late in the 17th century. It was cultivated as a source of blue dye
and has since naturalized as a weed of dry areas in our region. Dyer's woad
spreads primarily by seed.
DESCRIPTION: Dyer's woad can be a winter
annual,
biennial, or
short-lived perennial.
Basal leaves arise from thick
taproot, are lightly
pubescent, have long
petioles, and are up to 8 inches long. Stem leaves
clasp the stem and are lance shaped, not pubescent, and shorter than the
lower leaves. Leaves all have prominent whitish midvein. Stems are up to 4
feet tall and bear 1/4-inch wide, yellow flowers in flat-topped clusters
during May and June. Fruits are teardrop shaped, 3/4 inch long, purplish
brown at maturity, pendulous, and each contains a single seed.
 DISTRIBUTION: Dyer's woad is occasionally found in the eastern U.S.,
but is in the West where it is a serious weed. Dyer's woad is prevalent in
central and many of the southern Idaho counties.
CONTROL: No biological control agents are available for dyer's woad,
but herbicides are available.
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© 1999 University of Idaho:
Text and photographs for these pages from Idaho's Noxious Weeds, by
Robert H. Callihan and Timothy W. Miller (revised by Don W. Morishita
and Larry W. Lass).
Please contact: Ag Publishing, University of Idaho, Moscow, Idaho
83844-2240; 208 882-7982;
cking@uidaho.edu; or visit the Resources for Idaho website at
http://info.ag.uidaho.edu, for more information about this or other
publications. |
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