紅葉

1. Origins, structure, and basic meaning

• Structure: 紅葉 is read as もみじ and is a noun for a maple tree whose leaves color in autumn or for a maple leaf.
• Basic usage: A garden maple turning color appears in 庭の紅葉が色づく, while a fallen maple leaf appears in 落ちた紅葉.

2. Common pitfalls and similar expressions

• Context distinguishes the tree from the leaf
  • As something growing in a garden it refers to a maple tree, while as something fallen or floating it refers to a maple leaf.
• Same spelling with another reading: 紅葉（こうよう）
  • Read as こうよう, the spelling denotes autumn leaf coloration or foliage generally, whereas the reading here is もみじ for a maple or maple leaf.