柳树
liǔ shù · HSK 7
willow
🌳 柳 willow + 树 tree; 柳 liǔ sounds like leaves drooping low
柳树 pairs 柳 (the willow species) with 树 (tree), the generic word added to many plant names. The drooping-branch willow; 柳 alone already means willow, so 柳树 is literally willow-tree.
树 — wood 木 + 對 (phonetic, simplified to 对)
树 originally combined 木 'tree' with 尌, suggesting planting something upright. The right side served mainly as a phonetic clue, while 木 carried the meaning. Over time it came to mean both 'tree' and the verb 'to plant' or 'establish'.