​A bit of plant science, a bit of optical physics, fluid dynamics, a bit human emotion and physiology

​

Guttation: Fluid exuded from the tip, edges or surface of a leaf to relieve water pressure. 

Optical Physics: The image in droplets looks upside down due to refraction.

Fluid Dynamics: Guttation fluid and human tears are both examples of gravity-driven ejection, droplets forming at the tip start to fall under gravity after reaching the critical mass.

​

(I also remember reading that some hormones in guttation fluid and human tears are similar, but I can't find the reference. Human tear composition changes depending on the cause of tear production: sad tear, irritation tears, etc all have different chemical composition.)​​