They generally sell the plant in tiny little pots of water with an oriental flavour. I think mine originally came from a diy shop and I quickly disposed of the pot and put it in a bigger container because if I can't see the waters gone down then I know I won't keep it topped up.
You can get them in different stem lengths from tiny 3-4" sections which have been neatly tied together, to longer one. I think mine were about a foot and they went into a ten inch high tank and just sat on the substrate level so the growth tip was 3-4" above the waters surface. I liked the security of having the roots on the substrate, plus it hid the roots more, but they are happily with just their feet dangling in open water.