Flowers and leaves illustrated to be found as vector files in Vecteezy.
Some of the flowers:
wisteria, petunia, decorative hot pepper plants, ivy
https://www.vecteezy.com/vector-art/175020-free-exotic-leaves-2-vectors
https://www.vecteezy.com/vector-art/145872-free-exotic-leaves-vectors
https://www.vecteezy.com/vector-art/173665-palm-leaves-vectors
https://www.vecteezy.com/vector-art/146766-free-garden-flowers-vectors