The wide range of temperature fluctuation in different parts of the country and the multiplicity of climatic zones make it possible to cultivate a diverse variety of crops, including cereals (wheat, barley, rice, and maize (corn)), fruits (dates, figs, pomegranates, melons, and grapes), vegetables, cotton, sugar beets, sugarcane and pistachios (World's largest producer with 40% of the world's output in 2005), nuts, olives, spices e.g. saffron (World's largest producer with 81% of the world's total output), raisin(world's third largest producer & second largest exporter), tea, tobacco, Berberis(world's largest producer) and medicinal herbs. More than 2,000 plant species are grown in Iran; only 100 of which are being used in pharmaceutical industries. The land covered by Iran's natural flora is four times that of Europe.