heliotrope: [17] The heliotrope, a plant of the forget-me-not family, gets its name because its flowers always turn to face the sun (the word comes via Latin hēliotropium from Greek hēliotrópion, a compound formed from hélios ‘sun’ and -tropos ‘turning’ – as in English trophy and tropical – which designated such plants, and was also used for ‘sundial’).
In early times the word was applied to the ‘sunflower’, which has similar heliotactic habits and in Italian is called girasole (literally ‘turn-sun’), source of the Jerusalem in English Jerusalem artichoke. Another application of Greek hēliotrópion carried over into English was to a sort of green quartz which was believed to turn the sun’s rays blood-red if thrown into water. => trophy, tropical
