Water droplet on the edge of a leaf –
The house plant Philodendron White Measure has, on occasion, shed a few tears. Right-hand picture is a close-up of the same leaf shown in left-hand pic.
This is known as ‘guttation’.
Here’s the definition :-
gut·ta·tion | \ ˌgə-ˈtā-shən \
Definition of guttation
: the exudation of liquid water from the uninjured surface of a plant leaf