This is one of my favourite vegetables.
When I dug my pond, a couple of years back, a friend told me you could grow watercress just by throwing it in the pond. So I got a bunch out of the fridge and threw it in. They were right, it completely took over!

But I’ve never eaten my watercress, for fear of the danger. No cows or sheep live by my pond (it’s a town garden) so there’s little danger of the deadly liver fluke. My garden is also free from industrial or agricultural pollution. All the same, watercress is supposed to grow in free running water, and (although a solar pump cyles it) the water in my pond isn’t really fresh.
Then I ran across a post at The Cottage Smallholder, which described how you could grow watercress in pots, from seed. I also found this description of growing it in a plastic paddling pool! So if you can do that, maybe my watercress is alright after all?
Now I’ve harvested a few stems, soaked them in brine, and left them in fresh water overnight. My friend (who knows about these things) and I have consumed them.

If I don’t survive, I’ve asked for a warning to be appended to this post, so others may learn from our foolishness. But it was delicious.