In the Hindu epic Ramayana, Sumitra (सुमित्रा) was third of King Dasarath’s three wives. King Dasaratha had three Queens – Kaushalya, Kaikeyi and Sumitra.
She was the youngest Queen and the mother of twins Lakshmana and Shatrughna. She was considered to be the wisest of the wives of Dasarath. She was the one to first realize that Rama was the avatar of Lord Vishnu.
She even encouraged Lakshmana to go along with Rama and serve him throughout his exile.
Sumitra told Lakshman, “Ayodhya is where Rama lives, just like the sunlight being present only where the sun is. If Sita and Rama are going to the forest, there is no reason for you to stay in Ayodhya.”
Rani Sumitra : Tale of Twins in Valmiki Ramayana
There’s a well-known tale about why twins were born to her. Dasarath, despite having three wives didn’t have any children. None of the queens was able to give heir to the Ikshvaku dynasty.
The idea of his dynasty ending with him saddened Raja Dasarath and he was very desperate to have a son who can look after Ayodhya.
Rishi Vasistha who was the raj (royal) purohit of Ayodhya asked the King the reason behind his sadness and the King conveyed his worries about the lack of a male heir to his dynasty.
Rishi Vashisht organized a yagya and gave a plate full of sweets to both, Kaikeyi and Kaushalya and requested them to share their plates with the 3rd queen Sumitra.
This is the reason she gave birth to twins. Kaushalya and Kaikeyi were blessed with one son.
Rishi Vashisht named the twins as Lakshmana and Shatrughna.
Sumitra literaly means a good friend. Kaushilya and Kaykaie were the two consorts of Raja Dashrath.
That is why the prasad given by the sages after the Putrayeshti yagya was divided between the two consorts ignoring Sumitra . Lakshman was conscious about the status of her mother as being a good friend of the King and not the consort . That was one more reason why he accompanied Rama and Sita to the forest during their exile.
Some scholars are of the view that Manthara was jealous as she equated herself with Sumitra , both being non-consorts in the palace .