Maize (Zea mays L. ssp. mays) is a cereal grain that was domesticated in Mesoamerica and then spread throughout the American continents. It spread to the rest of the world after European contact with the Americas in the late 15th century and early 16th century. The term maíze derives from the Spanish form of the Arawak Native American term for the plant. However, it is popularly called corn in the United States, Canada, New Zealand, and Australia. Corn is a shortened form of "Indian corn", i.e. the Indian grain. The English word "corn" originally referred to a granular particle, most commonly cereal grains. It is called mielies or mealies in southern Africa. Hybrid maize is preferred by farmers over conventional varieties for its high grain yield, due to heterosis ("hybrid vigor"). Maize is one of the first crops for which genetically modified varieties make up a significant proportion of the total harvest. While some maize varieties grow 7 m (23 ft) tall at certain locations (Kuleshov 1933), commercial maize has been bred for a height of 2.5 m (8 ft). Sweetcorn is usually shorter than field-corn varieties