Not that it really matters, but the article also refers to it as “drawing water to the top”. That seems more representative of reality than “pumping water from the bottom”.

more like capillary action.

https://en.wikipedia.org/wiki/Xylem#Cohesion-tension_theory

They do wave in the wind, and evolution is likely capturing some of that motion for work.

“Trees contain lots of thin, hollow vessels and they suck water upwards by creating low pressure at the top,”

So sucking / pulling?