Bulbasaur is a small, quadruped Pokémon that has green to bluish-green skin with darker green patches. It has red eyes with white pupils and pointed, ear-like structures on top of its head. Its snout is short and blunt, and it has a wide mouth. A pair of small, pointed teeth are visible in the upper jaw when its mouth is open. Each of its thick legs ends with three sharp claws. On its back is a green plant bulb, which is grown from a seed planted there at birth. The bulb provides it with energy through photosynthesis as well as from the nutrient-rich seeds contained within.
Bulbasaur appears to be based primarily on some form of reptile, specifically mammal-like reptiles known as Dicynodonts from the Permian period. Along with visible ears and no genuine metamorphosis stage (evolution aside), Bulbasaur appears to have more in common with mammals than amphibians such as frogs and toads, which metamorphose from one definite creature into another as they mature as opposed to just growing into a larger adult version of itself the way that Bulbasaur does. Alternatively, Bulbasaur's large rounded snout, wide mouth, wide-set eyes, blotch-patterned skin, and quadraped-like movements are vaguely similar to those of certain amphibians, such as the common toad. Since Bulbasaur's "ears" do not in fact have hollows, they may actually be similar to the glands present behind the eyes of many species of frogs and toads.
The bulb on its back may resemble that of a lily or onion.