Amaranthus caudatus is a species of annual flowering plant.This species, as with many other of the Amaranths, are originally from the American tropics. The exact origin is unknown, as A. caudatus is believed to be a wild Amaranthus hybridus aggregate.A. caudatus can grow anywhere from 3 to 8 feet in height, and grows best in full sun. It can handle a variety of conditions, both humid and arid. It is easily grown from seed; plants can be started indoors in early spring and transplanted outdoors after the last frost.