hygro-, hygr- +

(Greek: moist, moisture, wet, damp)

Orientation, or movement, in response to humidity or moisture.
panhygrous (adjective), more panhygrous, most panhygrous
Relating to being moist all over or wet in all parts.
Organisms adaptable to a narrow variation in atmospheric humidity.
A reference to an organism that thrives in moist substrata.
In biology, thriving on moist substrata or sediment (subsoil), or the medium to which an organism is attached or upon which it grows.

Cross references of word families that refer to "water": aqua-; hydat-; hydro-.