Last year I attempted to grow a patch of grain type amaranth using seed I'd purchased from the bulk food section of a local health food store. It didn't grow very well, so I scoured my boxes of seeds for all amaranths I had of any type. This row is the result. From right to left: not visible behind the tall purple - are very short plants of 'Calaloo' (Amaranthus tricolor); the dark purple is 'Hopi Red Dye'; next is light green "Love-Lies-Bleeding" (Amaranthus caudatus); then an equally short stretch of purple 'Polish'; the long stretch of mixed purple and green that follows is a mixture of various grain types (including: 'Guarijio', 'Chinese Giant', 'Mercado Dreadicus', 'Manna de Montana', and 'Burgundy'), finally the miserably short little ones on the far left are 'Elephant Head'.
As well as the local weed (Amaranthus retroflexus) can grow around here, there shouldn't be any reason that I can't select for a locally adapted grain type of amaranth. Ideally this will grow like mad, have light-colored seeds and darkly pigmented leaves. For now, I'm just going to let them intermingle how they please. Later hopefully I'll have various vigorous descendants to start selecting from.