Do you call a maple Momiji (モミジ) in Japanese?
Yes, we do.
Momiji is written as “紅葉” in kanji. This word can be read in two ways: Momiji and Kouyou.
Momiji is a maple.
We can say “Momiji ga kirei.” (紅葉がきれい, A maple is beautiful)
Kouyou describes the phenomenon of the color of leaves turning red or yellow. We can say “Ha ga Kouyou suru.” (葉が紅葉する, Leaves turn red)
Both of these make Japanese people imagine autumn/fall.