Olive (Olea europea) is the most widespread cultivated tree in Greece. Olive trees alone, or in orchards, are found in all parts of the country that have a mild Mediterranean climate. The olive tree is considered to be one of the least demanding cultivated trees in terms of soil nutrients. For this reason, it is planted in poor, rocky areas with soils mostly derived from hard limestone. In traditional systems, practically all olive trees came from wild plants which were grafted. Edible olives and olive oil are the main products of olive trees, while secondary products include fodder for animals and firewood.