This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 桘 is uncertain. It visually combines 木 (tree/wood) with 台, but the original semantic and phonetic roles are unclear.
The left side is a tree 木, and the right side looks like a platform 台. Picture a wooden platform, but remember the meaning is uncertain.
For ツイ, imagine two trees (ツイ sounds like 'two-ee') on a platform: two trees -> ツイ.