- Scientific name: Isatis tinctoria
- Family: Brassicaceae (cabbage, broccoli)
Biennial herb up to 1m tall. Leaves entire, up to 10cm long, oblong-lanceolate, some leaves clasp stem. Flowers in loose racemes, four yellow petals. Fruits up to 2.7cm long, oblong-obovate. Pollinated by insects.
- The leaves of this plant are the source of a blue dye, often used instead of indigo.
- Leaves are collected from flowering stems, dried in the sun, ground into paste and left to ferment. This produces a smell so disgusting that it was an offence in Tudor times to dry woad near the royal palaces. The fermented leaves are then formed into cakes, mixed with water and fermented again. The colour is drawn out by infusing the woad with lime water.
- As well as being used for clothing, woad was once used by Celtic warriors to stain their bodies during battle. Some historians think the word Britain came from this custom of war-painting, as the old Celtic for paint was Brith and Brithon meant stained man.
Where it grows
Woad is thought to be native to southern Russia, but it escaped cultivation and has now naturalised throughout most of central and southern Europe. It can be found on cliffs and in cornfields, often in chalky soils.
- Biennial: takes two years to mature.
- Herb: plant with fleshy parts rather than a persistent woody stem above ground.
- Lanceolate: narrowly ovate and tapering to a point.
- Obovate: two-dimensionally egg-shaped with widest part at the apex.
- Raceme: a flowering structure where the individual flowers are clearly stalked, the newest and last to open being at the apex.