The Sapleaf evolutionary line came from the fact that the game seemed lacking in Grass, Fire and Ghost type Pokémon, and one 4chan poster jokingly said there should be an evo-line where they started Grass, became Fire and then became Ghost. Little did they know, the idea would be taken seriously.
Its cry sounds like it is screaming in pain, referencing Sapleaf being burnt alive as an Ignut.
Ignut and its evolution line are the only Pokemon to both be in the Grass and Mineral Egg Groups.
Ignut's name comes from the words "ignite" and "nut".
It's a Sapleaf being burnt alive. Based on the "nut" part in its name, it may also be based off a nut.
My friend also pointed out how it resembles a pumpkin slightly.
Not too sure which retard had to add that ^ up there, but this doesn't teach anybody anything, so shut the fuck up and get laid you reddit user.