Deku Babas, Deku Sticks and Deku Nuts
Deku Babas are carnivorous plants that appear throughout The Legend of Zelda, starting with Ocarina of Time. They are often found in forested areas and are fairly standard as far as video game enemies go, but there may be more in the form of their relation to other forest creatures.
In my recent post about the life cycle of forests in The Legend of Zelda, I concluded that Deku Nuts are likely the seeds of the Great Deku Tree that can either sprout into Forest Trees or Koroks. According to the Japanese magazine Nintendo Dream, Deku Babas are originally nuts of the Great Deku Tree that became carnivorous plants after feeding on evil in the soil. Magazines like Nintendo Dream are often dubious sources at best when it comes to lore information given their distance from the original developers and penchant to make up new information without it being clear where that information comes from. However, in this case, there may be a basis in the games.
Deku Babas in Ocarina of Time drop Deku Sticks when defeated, which are branches of the Great Deku Tree according to their description in the Kokiri Shop. This would indicate the stalk of a Deku Baba may be a Deku Stick and its head could be a Deku Nut. This is further solidified in Twilight Princess, where Deku Baba heads harden after being defeated. They leave behind a nut that is very similar to the Deku Nuts from Ocarina of Time and Majora's Mask.
How much this extends to other incarnations of Deku Babas from throughout the series is a bit unclear, though the fact that Deku Babas in Skyward Sword drop Deku Seeds may also hint at this relationship. Deku Seeds in Skyward Sword do look similar to Deku Nuts, though their exact relationship is unspecified. Perhaps they are an earlier stage of development for Deku Nuts.
The idea that creatures from the Light World can be corrupted into demons is a common one in Zelda, as shown chiefly with the human Ganondorf becoming a Demon King and sometimes a Demon Beast. It also extends to some enemies like the inhabitants of the Dark World from A Link to the Past, and likely thus also to Deku Nuts and Sticks that together form Deku Babas.
