Religions that recognize the existence of plant souls include Jainism and Manichaeism.
The Ācārāṅga Sūtra states that "plants ... and the rest of creation (experience) individually pleasure or displeasure, pain, great terror, and unhappiness" (1.1.6).
(Note that the pronouns "this" and "that" in Hermann Jacobi's original 1884 translation have been substituted with "men" and "plants".)
The Cologne Mani Codex contains stories showing that Manichaeans believed in the existence of sentient plant souls.
[3] Fynes (1996) argues that Jain ideas about the existence of plant souls were transmitted from Western Kshatrapa territories to Mesopotamia and then integrated into Manichaean beliefs.