On the Damper to Wetter Side

I have quite a bit to write about moisture requirements, but until that happens, here is a useful list for your consistently damp to wet areas. Not all of these want to stand in water, although some of them do. Some of them simply prefer consistent moisture, but are quite accommodating, so I also suggest reading the plant descriptions for further details. For certain plants, if sunlight is reduced often water needs can be reduced to no ill effect. If you do not have a pond, stream, marsh, or damp garden, but want to grow some of the most water-loving plants, I suggest trying containers. In a container, all conditions can be satisfied. You can make a little water garden or bog garden, or just keep your eye on a group of plants that want more moisture than the skies are providing where you live. Any way that you can introduce even small amounts of water into your garden is an immense boon to all the creatures living there. 

What I will say right now is that plants want to grow and will grow in surprising places, often where humans did not think they could manage, so don't get too rule bound. Observe and take note of the specific conditions.