The force of gravity makes things fall to earth.

心引力使物体落向面。

The geotropism growth was a response of hypha to gravity and the geotropic sensitive was at the hyphal apex.

丛枝菌根真菌菌丝延伸生长部位是菌丝尖端，其生长的向是对心引力的感应，感应的敏感部位也在生长菌丝的尖端。