Like duckweed, it is native to the US, and where you find it - there is a ton of it. It can be seen in huge mats covering a cove of a lake. It is often green, but in cool weather it can be a brilliant maroon color. You rarely see it in LFS b/c it doesn't hitchhike quite as well as duckweed. I also love this plant, but needs constant removal or it will shade the entire tank.