Hygroscopic

Sodium hydroxide is quite hygroscopic.

The tissues of Ralfsia are dense and the cells are extremely hygroscopic. The plants may become almost crisp dry in the sun, yet remain alive and continue growth with the first splash of the incoming tide.

All fertilizers tested are drillable at relative humidities below 50 per cent, but no fertilizer remains drillable when exposed to a humidity above its hygroscopic point.