Turmeric

*Curcuma longa*

How to know it

Above ground it looks unremarkable, broad green leaves on a short stem, easily mistaken for a young ginger. The interest is entirely below the soil, where the rhizome is a vivid orange.

What it does

Turmeric is used in cooking, as a fabric dye, and traditionally as an anti inflammatory across South and Southeast Asia. The colour comes from curcumin. It stains hands, cloth and worktops with real determination, which is either a problem or the point of the lesson.

Safety

Safe to handle and eat. It stains skin yellow for a day or two, and it stains clothing permanently. Warn parents before a turmeric session.

Two things to do with children

Dig one up. The gap between the dull plant above ground and the orange root below is the surprise, and it teaches that the useful part of a plant is not always the obvious part.

Dye a square of white cotton. Boil grated turmeric, soak the cloth, dry it in the sun. Children keep those squares.