Hello and thank you for your question! This plant really looks like a poinsettia, doesn't it?
It is actually an ornamental annual called Joseph's Coat amaranth. The botanical name is Amaranthus tricolor.
There are a large number of amaranth varieties; the original plants were cultivated for grain as far back as the Aztec civilization, and it is still grown today for food.
The Joseph's Coat amaranth is not grown for food, but for the high ornamental value. It can be used as a specimen plant to draw attention, in mass plantings and in ornamental borders. It is fairly easy to grow from seed, but it only lasts until the end of the season and then it dies.
If you are interested in knowing more about this plant, I've put a link to a fact sheet with more information:http://edis.ifas.ufl.edu/fp038#FIGURE%201
I hope this answers your question! If not, please feel free to call the Spokane County Master Gardeners at 509-477-2181 or email us at firstname.lastname@example.org.