amaranth, red amaranth, and Mexican grain amaranth. Amaranthus cruentus is a tall annual herb topped with clusters of dark pink flowers. The plant can grow up to 2 m (6 ft) in height, and blooms in summer to fall. It has now naturalized in most states. It is believed to have originated from Amaranthus hybridus, with which it shares many morphological features. This species was in use as a food source in Central America as early as 4000 BC. The plant is usually green in color, but a purple variant was once grown for use in Inca rituals.