Tree: 木 (5)
木 is called きへん when it sits on the left, and often points to trees or wooden things. 楠 is a camphor tree and 槻 a zelkova; 桟 also uses wood in a built structure, while 朽 means decay, as wood can rot.
朽 has 6 strokes and 桟 has 10. In this family, keep the left-side 木 compact so it leaves room for the rest of each character.