What kind of plant does the "weatherman" in the tree mean?

There is an elm tree in Dateng Village, Gaoguan Township, Hexian County, Anhui Province. Surprisingly, this elm tree is a "meteorological tree" that can predict the drought and flood in that year.

People can infer the rainfall of that year according to the time of germination and the density of leaves of this tree. If this tree sprouts and grows leaves in front of Grain Rain, it means that there was much rain, high water level and frequent floods. If it, like other trees, germinates in season and leaves grow sparsely and densely, then it will be a good year with good weather; If the germination is delayed and the leaves grow less, it means that there was less rain and serious drought in that year. Decades of observation data prove that it is quite accurate to predict the drought and flood in that year.

After a preliminary investigation, scientists believe that this may be because this tree is particularly sensitive to the ecological environment, which will play this strange role.