Why is Tulsi and Ashwattha important in the Vedas?

Vishnu's influence is very extensive in Hindu life. From stone to tree-taru gets divinity under that influence. Along with the shalgram rock, Tulsi and Ashwattha are worshiped from house to house as forms of Narayana.

Tulsi tree is popularly known as 'Hari tree'. This context is mentioned in an anecdote of Brahmavaivarta Purana. Tulsi tree was born from the hair of Krishnapriya Sankhachupadni Tulsi. Tulsipatra is essential in the worship of Vishnu in the form of salgram. In Goloka Vrindavan, Gopika Vrindadevi, Tulsi is the constant attendant of Radhakrishna and the main conductor of their various divine lilas.

He is an ambassador of Krishna, an expert in Kunjadi Sanskar and a scholar in Ayurveda Shastra. She is known as Tulsi because she is the purest form of all goddesses and has no equal in the entire world.

Ashwattha tree is also worshiped as Narayana. Irrigation of Ashwattha trees is considered a meritorious act. The Upanishad says,

ঊর্ধ্বমূলোহ বাকশাখ এষোহশ্বত্থঃ সনাতনঃ।

তদেব শুক্রঙ্গ তদব্রহ্ম তদেবামৃতমুচ্যতে।

তস্মিল্লোঁকাঃ শ্রিতা সর্বে তদু নাত্যেতি কশ্চন এতদ।

That is, the root and the lower branches are the Sanatana Aswattha tree. He is Shukra, He is Brahma, He is called Amrita. He is the seat of all people, none can surpass Him. This is him.

This horse is also mentioned in Bhagavad Gita.

The upper branch Ashwattha is called Abaya (Brahma), all the Vedas are its leaves. He who knows Him is a Vedavit. Ashwattha is called the Narayan tree because it is likened to Brahma.

In the Rigveda, Yamadeva lives with other gods in a tree, that too Asvattha. Hinduism believes that God resides in all parts of this tree. Ashwattha tree is also called Chaiti tree, Vishwa tree and Vasudeva.

In the Srimad Bhagavad Gita, Sri Krishna says, I am Ashwattha among the trees. Lord Brahma resides at the root of the Ashwattha tree, Lord Vishnu resides at the trunk, Lord Shiva resides at the top of this tree.

Again according to the Skanda Purana, Lord Vishnu is at the root of the Asvattha tree, Kesava is in the trunk or middle, Narayana is in the branches, Lord Srihari is in the leaves, and all the deities reside in all the fruits. In the Atharvaveda and the Chandogyopanishad, the lower ground of the Asvattha tree is called the heaven of the gods.