#01 Bulbasaur -- Pokedex Series (Patreon)

"A strange seed was planted on its back at birth. The plant sprouts and grows with this Pokémon. It can go for days without eating a single morsel. In the bulb on its back, it stores energy. The bulb-like pouch on its back grows larger as it ages. The pouch is filled with numerous seeds." (Pokemon RBYSt)