It can be used in many ways. Check out Amaranthus.

All amaranths and related pigweeds are edible when young as a spinach substitute. Some cultivated varieties have been developed to produce edible leaves for the life of the plant while other varieties are "grain" producers. Then, of course, there are ornamental ones.

Amaranthus tends to self-seed if you allow the plant to grow through the seeding stage. At my market farm we allow some of these volunteers to co-exist with our crops because they are pretty, serve to attract birds, and can be fed to the chickens at any time.

When I looked at this post, I thought my mind was going. Then I remembered I'd posted to it on the veggie forum. A briefer version of what I wrote there - 'Joseph's Coat', Amaranthus tricolor, is also known as Chinese spinach, Een choi etc. and is a very popular green in Asia.

I eat mine, but it's very bitter when it gets older.