Why Tulsi had to marry demon Shankachuda?

One day while roaming on the banks of Ganga Tulsi saw Ganesh Ji in deep meditation. She got infatuated with Ganesh Ji. She broke the meditation of Ganesh Ji and asked him to marry her. Ganesh Ji in anger strongly refused saying he was not interested in marriage. Tulsi tried her best to somehow persuade Ganesh Ji but he didn't budge from his position. Angered Tulsi cursed Ganesh Ji that he will have to marry in future. Ganesh Ji in return cursed Tulsi that she will have to stay in homes of demons and become a plant. Frightened she requested Ganesh Ji to forgive her. Ganesh Ji relented and told her that in future she will become the favourite plant of Krishan Ji. So Tulsi had to marry demon Shankachuda and later become a plant.