Everyone know that many deities took incarnation as humans, devas and sometimes animals. But, Did any deities incarnate as demons and plants?
Sri Shiva Purana 126.96.36.199.:
- Out of the seeds sown (on Vrinda's pyre), O great sage, three plants shot up—the Myrobalan, the Jasmine and the holy basil (Tulsi).
- Sankhachura is a partial incarnation of Lord Vishnu who is Sudama. Mata Lakshmi became Tulsi.
Srimad Devi Bhagwatam 9.6.:
- O Lakṣmī! Let you be born in parts, without being born in any womb, in the world as the daughter in the house of the King Dharma-dhvaja. You will have to take the form of a tree there, out of this evil turn of fate. There Śaṅkhacūḍa, the Indra of the Asuras, born of my parts will marry you. After that you will come back here and be my wife as now. There is no doubt in this. You will be named Tulasī,...
I hope this helps. Prd..
As per Chapter 60 of Kalika Purana, Mahishasura is said to be a partial incarnation of Shiva in a certain kalpa.
As per the text, He is said to have taken this partial form in order to bear Devi alongside Simha-rupi Vishnu.
Laxmi is suppose to be born as Tulsi. https://en.wikipedia.org/wiki/Tulasi_in_Hinduism