Butterfly Pea

*Clitoria ternatea*

How to know it

A thin climbing vine with soft green leaves and an unmistakable deep blue flower shaped like a small folded shell. There is a white variety too. It climbs anything and grows fast enough to cover a fence in a season.

What it does

The flowers are steeped to make a brilliant blue drink. Add lime juice and it turns purple, then pink. That colour change is a pH reaction, and it is the most reliable piece of visible chemistry you can run with a five year old. The blue is used to colour rice and cakes across the region.

Safety

Flowers and leaves are safe. The seeds and pods are not eaten and should be kept out of reach of very young children.

Two things to do with children

Steep six flowers in hot water, let it cool, then hand each child half a lime. Squeezing it in and watching the colour change is the whole lesson.

Grow it up a fence and let children pick flowers themselves. It flowers continuously in warm weather, so there is always a supply.

Worth knowing

Blue is the hardest colour to find in a tropical garden. Planting this solves the problem for every colour hunt sheet you will ever run.