Tulsi or Tulasi (Holy Basil) is considered to be a sacred plant in Sanatan Dharma , Now Hinduism.
Tulsi or Tulasi (Holy Basil): According to Sanatan Scriptures, during the Samudra Manthan (churning of the ocean of milk), Srihari emerged from the ocean in the form of Dhanvantari, the heavenly physician carrying the pot of Amrita, the nectar of immortality. It is said that a few drops of Srihari’s tears of joy fell into the pot, and Tulsi was born out of these tears of joy.
Hailed as the threshold between heaven and earth, Tulsi is said to hold the following: • Brahma residing in its branches • The Hindu centres of pilgrimage residing in its roots • The holy river Ganga flowing through its roots • All the other deities in its stem and leaves
The tip of the plant is said to have the holy scriptures, the Vedas in them.
Most Hindu households have a Tulsi plant in their courtyard. Tulsi (meaning matchless) is also known as Vaishnavi (belonging to Vishnu) and Vishnu Vallabha ( beloved of Vishnu). Tulsi with green leaves is known as Rama-Tulsi, while the one with dark green or purple leaves is called Krishna-Tulsi (dark Tulsi).
According to mythology, Tulsi was the devoted wife of Shankhachuda, an Asura (Demon) who was terrorizing the Devas (Gods). He had a boon from Brahma that, as long as his wife stayed chaste, he will be invincible . When the Gods approached Lord Vishnu for help, he took on the form of Shankhachuda and broke Tulsi’s marriage vows. The Devas killed Shankhachuda, and Tulsi cursed Lord Vishnu for his duplicity, turning him into a stone.
Lord Shiva’s blessings to Tulsi ensured that she would always remain as beloved to Lord Vishnu. This is the reason why Tulsi is worshiped along with Lord Vishnu who takes the form of a stone – Saligram.
The Sanatan scriptures which is now known as Hindu scriptures, prescribe that offerings to Lord Vishnu and his various avatars, including Rama and Krishna, would be incomplete without an offering of the Tulsi leaves.