turnsole

noun

1. The heliotrope; so named because its flowers are supposed to turn toward the sun.

2. The sunflower.

3. A kind of spurge (Euphorbia helioscopia).

4. The euphorbiaceous plant Chrozophora tinctoria.

5. A purple dye obtained from Chrozophora tinctoria.

6. (chemistry, obsolete) litmus