Even without they’re pretty darn resistant, and proof against rain or, e.g., dropping one in a puddle or off your kayak and then fishing it out immediately. Just don’t try to use one as a time capsule that’ll be exposed to the elements indefinitely, or expect the contents to survive being immersed forever at the bottom of your aquarium.

They’re definitely not airtight, either. Which may be a factor for storage of your… herbaceous materials.