This is most likely a map error. These types of maps that change shape every X minutes work like this: a first version of the map is made, then a copy of it is made with some modifications.
Let's assume that map was originally created in the day version and modified for the night version. In the case of this plant it is something that players cannot walk over.
Taking this into account, it is likely that the mapper forgot to place this plant in the nighttime copy of the map and then, when the map changes and the player stays in that square, the game will understand that there was a problem (similar to what happens at the doors of Ebb and Flow) and will send the player to the temple.