Amaranths sometimes hybridize. When I saw this tall one, it didn't seem to check out as any species. I decided it was probably a hybrid. But ultimately I learned that mat amaranth doesn't always grow in mats. Apparently it's not completely reconciled to hugging the dirt in barren places where the wind can reach the ground. I wonder if it only sends up taller stems when it's crowded by other wind-blocking plants? If so, it's pretty smart!