Isatis tinctoria |
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asp-of-Jerusalem, dyer's woad, woad |
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Habit | Plants glaucous, usually glabrous, sometimes pubescent proximally. |
Stems | (3–)4–10(–15) dm. |
Basal leaves | 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. |
Cauline leaves | blade usually oblong or lanceolate, rarely linear-oblong, base sagittate or auriculate, apex acute. |
Flowers | 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. |
Fruiting pedicels | 5–10 mm. |
Fruits | 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. |
Seeds | light brown, 2.3–3.5(–4.5) × 0.8–1 mm. |
2n | = 14, 28. |
Isatis tinctoria |
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Phenology | Flowering Apr–Jun. |
Habitat | Roadsides, fields, pastures, sagebrush hillsides, prairies, railroad embankments, waste places |
Elevation | 300-2200 m (1000-7200 ft) |
Distribution |
CA; ID; IL; MO; MT; NM; NV; NY; OR; UT; VA; WA; WV; WY; BC; NF; ON; QC; Europe; c Asia; sw Asia; n Africa [Introduced in North America; introduced also in South America (Chile, Peru)]
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Discussion | Isatis tinctoria 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. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 7, p. 568. |
Parent taxa | Brassicaceae > tribe Isatideae > Isatis |
Name authority | Linnaeus: Sp. Pl. 2: 670. (1753) |
Web links |
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