In nature plants gain life energy primarily from sun, water, minerals and gases.
Animals gain energy primarily from plants and other animals; however they also need sun, water, minerals and gases.
Though these 2 groups really depend on each other, mutually favorable direct metabolistic interactions scarcely exist in nature.

My idea is to create a symbiotic pair of creatures consisting of a primate animal and a plant. The plant would consume minerals and water consumed by its animal symbiote and produce dextrose using the sun energy caught by its green plastids, then transferring it partially to the animal's organism, while the animal would provide it with minerals and water necessary and benefit from the plant by assimilating dextrose.
Realization of this idea is very difficult because of significant discrepancy between the metabolism speed of plants and animals and impossibility of adjusting animal's dynamic vegetative system to primitive plant's tropisms.

But if it was