The potato (Solanum tuberosum) is an herbaceous annual that grows up to 100 cm (40 inches) tall and produces tubers, which are botanically thickened stems that are so rich in starch that they rank as the world's fourth most important food crop, after maize, wheat and rice.
The potato belongs to the Solanaceae, and shares the genus Solanum with at least 1,000 other species, including tomato and eggplant. S. tuberosum is divided into two, only slightly different, subspecies: andigena, which is adapted to short day conditions and is mainly grown in the Andes, and tuberosum, the potato now cultivated around the world, which is believed to descend from a small introduction to Europe of andigena potatoes that later adapted to longer day conditions.