On the eleventh day of the month of Kartik during Prabodhini ekadashi, Indians celebrate the ceremony called Tulsi Vivah, the marriage of Tulsi, the sacred plant and Vishnu in the form of Shaligram shila, a stone. The shaligram shila is a ammonite fossil, which is located in Muktinath, in the bed of the river Gandaki in Mustang district in Nepal. It is considered an abstract representation of Vishnu.
In the Tulsi Vivaha, the ceremony recreates a uja called Kalyana Utsavam. A delicate wedding pavilion (mandap) is made with the stalks of sugarcane and a tulsi plant is decorated with a yellow wedding sari, although red is also the color common in Hindu weddings. It is adorned with jewels and red kumkum. The wedding takes place with the puja (prayer) of a complete wedding. The Tulsi plant is offered a feast of seasonal fruits, fresh tamarind, turmeric, amla (gooseberry) and rice.
Tulsi or Tulasi is a variety of basil that is considered sacred in the Hindu religion. It is also used for a variety of drugs and other medicinal utilities. Most Hindus usually offer daily prayers to Tulsi. However, many people are unaware of the origin of the plant Tulasi and because it is considered religious. There are many interesting legends about Tulsi, but I'm going to focus on the most compelling I found in the several religious texts as I read.
This festival marks the end of the monsoon and the beginning of the period of marriage for Hindus. It is quite popular throughout India but is usually held more in southern India. Vrinda or Tulsi is worshiped as Vishnupriya, and her story begins when she was married to Asura King Jalandhar. Not even Shiva could defeat him, and at last only a woman could kill him.
As a child his mother was killed before his eyes by the vajra weapon of Indra, and he swore revenge and so to destroy all the Deva warriors. He was raised by the invincible Asura Varuna, who was the king at that time.
He always defeated the Deva warriors, and a large part of the territory was under his control. He had a wonderful wife named Vrinda, who was a pure soul. Because of her purity she was the spiritual strength of Jalandhar, who became invincible.
Shiva sought help from Vishnu to permanently get rid of him and suggested him to do it through the wife of Jalandher. Vrinda, was very pious and the devotion to her husband was unconditional and was very protective of him. Vishnu, developed a plan and sent his messengers to tell Vrinda that her husband had died in battle. Vishnu took a fake dead body and made her believe that it was the body of her husband.
Vishnu, sneaked away and took the form of a sadhu and changed his appearance and deceived Vrinda, by forcing himself on her and taking her modesty away. Jalandher later rose from the ground. When Vrinda found her husband was alive and in front of her, she hugged him with passion and relief. However, she quickly realized her mistake and the deceit of Vishnu.
When she gets to know the whole truth about the death of her husband, she was mad with rage and was distraught at having been duped and cursed Vishnu to death, and, later, she walked away in despair of having been molested, without the knowledge of her husband, and, full of grief, she headed for the ocean seeking death.
Jalandher, mad with grief over the death of his beloved wife, tried in vain to take revenge and, after several attempts, was beaten and later killed by Kali.