Clytia

a water nymph, daughter of Oceanus and Tethys in Greek mythology.
Helios, having loved her, abandoned her for Leucothoe and left her deserted. She was so angered by his treatment that she told Leucothea's father, Orchamus, about the affair. Since Helios had defiled Leucothea, Orchamus had her put to death by burial alive in the sands. Clytie intended to win Helios back by taking away his new love, but her actions only hardened his heart against her. She stripped herself and sat naked, with neither food nor drink, for nine days on the rocks, staring at the sun, Helios, and mourning his departure. After nine days she was transformed into the turnsole, also known as heliotrope (which is known for growing on sunny, rocky hillsides),[3] which turns its head always to look longingly at Helios' chariot of the sun. The episode is most fully told in Ovid, Metamorphoses iv. 204, 234–56.

Modern traditions substitute the turnsole with a sunflower, which according to (incorrect) folk wisdom turns in the direction of the sun (the original French form tournesol primarily refers to sunflower, while the English turnsole is primarily used for heliotrope).