一顆根上 Nine Branches One Root
大聖聞言，即令土地回去，與八戒跳過溪來，尋那顆楊樹。果然有九條叉枝，總在一顆根上。大圣闻言，即令土地回去，与八戒跳过溪来，寻那颗杨树。果然有九条叉枝，总在一颗根上。
逐句解 Line by line
When the Great Sage heard this he sent the local god back, jumped across the stream with Bajie, and looked for that willow.
即令土地回去 — the god is dismissed the instant he has been useful, with no thanks. Wukong treats the celestial civil service exactly as a senior official treats a junior one, which is the joke and also the point.
Sure enough there were nine forking branches, all coming from a single root.
The tree is the one landmark in a grove of ten thousand, and the novel gives it thirteen characters. Nine branches from one root is a shape with obvious resonance in a chapter about one creature wearing many faces — though the book, as usual, points at nothing and lets the picture do its own work.
The search that filled the last five passages is over in two sentences. This is how the novel handles solved problems: once the information is in hand, the execution gets no more space than it needs.
Note that the god is sent away before the door is opened. Wukong has what he came for and has no intention of sharing the fight, or the credit, with a parish official who has just admitted he was too frightened to file a report.