This plant is listed by the U.S. federal government or a state. Common names are from state and federal lists. Click on a place name to get a complete noxious weed list for that location, or click here for a composite list of all
Federal and State Noxious Weeds
This plant can be weedy or invasive according to the authoritative sources noted below.This plant may be known by one or more common names in different places, and some are listed above. Click on an acronym to view each weed list, or click here for a composite list of
Weeds of the U.S.
Linnaeus, Sp. Pl. 2: 670. 1753.
glaucous, usually glabrous, sometimes pubescent proximally.
(3-)4-10 (-15) dm.
petiole 0.5-5.5 cm; blade oblong or oblanceolate, (2.5-)5-15(-20) cm × (5-)15-35(-50) mm, base attenuate, margins entire, repand, or dentate, apex obtuse.
: blade usually oblong or lanceolate, rarely linear-oblong, base sagittate or auriculate, apex acute.
sepals 1.5-2.8 × 1-1.5 mm, glabrous; petals 2.5-4 × 0.9-1.5 mm, base attenuate; filaments 1-2.5 mm; anthers 0.5-0.7 mm.
black or dark brown, often broader distal to middle, (0.9-)1.1-2(-2.7) cm × 3-6(-10) mm, base cuneate, margins sometimes slightly constricted, apex usually subacute or rounded, rarely subemarginate; locule with distinct midvein, lateral veins inconspicuous, 3-6(-10) mm; apical wing 3.5-5(-7) mm wide.
light brown, 2.3-3.5(-4.5) × 0.8-1 mm.
= 14, 28.
Flowering Apr-Jun. Roadsides, fields, pastures, sagebrush hillsides, prairies, railroad embankments, waste places; 300-2200 m; introduced; B.C., Nfld. and Labr. (Nfld.), Ont., Que.; Calif., Idaho, Ill., Mo., Mont., Nev., N.Mex., N.Y., Oreg., Utah, Va., Wash., W.Va., Wyo.; Europe; c, sw Asia; n Africa; introduced also in South America (Chile, Peru).
has been cultivated since ancient times as a source of a blue dye (woad) obtained by fermenting the ground leaves and proximal portions of the plant.
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