You will get enough evidence in SkandaPurana, Padma – Purana, Brahma Vaivarta – Purana and other Puranas regarding glory of Tulsi and advent of SreeVrinda Devi as ‘Holy Tulsi Tree’ in this world to grace the souls of this world by bestowing on them service of Sree Krishna and SreeNarayana.
 
Souls are deprived of the service of Sree Krishna, when they unfortunately become averse to Him due to misuse of relative independence. It is narrated in Brahma Vaivarta – Purana that Vrinda Devi appeared in this world as Tulsi accepting King Dharamadhwaj as Madhavi Devi as her parents on KartikaPurnimatithi as per desire of Sree Krishna and SreematiRadha Rani. As there was none equal to her in beauty, she was named ‘Tulsi’. Tulsi performed a pastime of severe penance to get Narayana as her husband and got the boon from Sree Brahma in regard to this. As per desire of SreematiRadha Rani, SudamaGop appeared in this world as ‘ShankhachuraDanava’, with whom Tulsi was married. ShankhachuraDanava seized ‘Swarga’ by his tremendous power. Demigods initially took shelter of Brahma, then Shiva and ultimately went to Vishnu for rescue from the oppression of ShankhachuraDanava.
 
Lord Vishnu appeared, killed Shankhachura and fulfilled the desire of Tulsi. Lord Vishnu conferred the boon to Tulsi that her body would become river Gandaki and her hairs would be Tulsi. Lord Vishnu appeared in this world as ShalagramShila.
 
Whatever the Will of Lord does is for the eternal benefit of all, as He is All-Good. Cow-dung (stool of cows), Conch-shell (bone of an animal) has become sacred by the Will of Lord. So what difficulty is there in believing ‘Tulsi’ as the Holy tree appearing in this world by the Will of The Supreme Lord Sree Krishna to bestow on us His service? There is nothing impossible for God Who is Omnipotent. God can appear in this world in any form He likes, for the eternal good of the enslaved souls, over whom He has got affection. You are to perform Tulsi Puja daily.