Amaranth is the name given to a group of approximately 70 species of annual or short-lived perennial plants in the genus Amaranthus including several species of aggressive edible weeds native to the US such as Amaranthus retroflexus (redroot pigweed). Amaranths are branching broad-leaved plants with egg-shaped or rhombic leaves which may be smooth or covered in tiny hairs. The leaves have prominent veins, can be green or red in color and have long petioles. The plants produce single flowers on terminal spikes which typically red to purple in color. Amaranths can reach up to 2.5 m (6.6 ft) in height and are usually grown as annuals, harvested after one growing season. Amaranth may also be referred to as Chinese spinach and their origin is unclear due to their worldwide distribution.