Potato

The potato is a starchy root vegetable native to the Americas and one of the world’s most important staple foods. It is the underground stem tuber of Solanum tuberosum, a perennial plant belonging to the nightshade family, Solanaceae. Wild potato species occur across a broad region stretching from the southern United States to southern Chile. Genetic research indicates that the cultivated potato originated once in pre-Columbian South America, specifically in the area corresponding to modern southern Peru and north-western Bolivia. Domestication took place between 7,000 and 10,000 years ago from species within the Solanum brevicaule complex. Numerous traditional varieties continue to be grown in the Andean highlands, where the crop has been part of Indigenous agriculture for millennia.
Following the Spanish conquest, the potato was transported to Europe in the late sixteenth century as part of the Columbian exchange. From there it spread across the world and became a foundational food crop. Today more than 5,000 cultivars exist, with the crop remaining vital in Europe—particularly in northern and eastern regions—and expanding rapidly in South and East Asia. China and India are the leading global producers. As with other members of the genus Solanum, potato plants contain glycoalkaloids such as solanine; although levels in properly grown and stored tubers are negligible, exposure to light—particularly in sprouting or green potatoes—can increase toxicity.

Etymology

The English word potato derives from the Spanish patata, itself originating from a Taíno term that referred to the sweet potato. The word spud entered English in the fifteenth century, originally describing a short, stout digging tool or knife; by the nineteenth century it had transferred semantically to the tuber itself. In several languages of Europe and beyond—including Afrikaans, Dutch, French, West Frisian, Hebrew and Persian—terms for potato translate as “earth apple”, reflecting an older sense of “apple” as a generic round fruit or edible plant structure.

Botanical Description

Potato plants are herbaceous perennials that typically reach substantial height depending on conditions. Their stems are hairy, and the pinnate leaves usually feature around four pairs of leaflets. The flowers vary in colour—white, pink, purple, or blue—with yellow centres, and are pollinated by insects. Below ground, the plant forms tubers, which are modified stems rather than true roots. Tubers develop at the ends of slender stolons and contain “eyes”, which are buds protected in small depressions arranged helically around the tuber. Lenticels—tiny pores—enable gaseous exchange. Flowering is followed by the production of small green fruits resembling cherry tomatoes, each containing hundreds of seeds, though these fruits are generally not used in cultivation.
Tubers form in response to shortening day length, a trait that has been reduced in modern commercial varieties. Their primary function is the storage of nutrients to sustain the plant through adverse conditions and to support regrowth.

Phylogeny and Species Diversity

Potatoes belong to the genus Solanum, which includes diverse and often toxic species such as mandrake (Mandragora), deadly nightshade (Atropa) and tobacco (Nicotiana). The main cultivated species is Solanum tuberosum, a tetraploid with 48 chromosomes. Several other cultivated or semi-cultivated species exist, including diploid forms such as S. stenotomum, S. phureja, S. goniocalyx and S. ajanhuiri; triploids such as S. chaucha and S. juzepczukii; and the pentaploid S. curtilobum. Two principal subspecies are recognised: S. tuberosum andigena, adapted to short-day conditions of equatorial and tropical highlands, and S. tuberosum tuberosum, native to the long-day conditions of the Chiloé Archipelago in southern Chile.

Domestication and Early History

Archaeological evidence indicates the earliest verified potato remains date to around 2500 BC from the coastal site of Ancón in central Peru. The Andean region, particularly around Lake Titicaca, served as the centre of early domestication. The variety S. tuberosum tuberosum, widely cultivated today, originates from the Chiloé Archipelago and was grown there by Indigenous peoples long before the arrival of Europeans.

Global Spread and Historical Impact

After being introduced to Europe in the late sixteenth century, the potato experienced slow adoption by farmers. By the mid-eighteenth century, however, it had become a valuable field crop and dietary staple. It played a significant role in Europe’s nineteenth-century population growth, with some estimates attributing roughly one-quarter of population expansion and urbanisation between 1700 and 1900 to the availability and nutritional value of the potato.
The initial narrow genetic base of European potatoes, however, left the crop susceptible to disease. In 1845 the late blight pathogen Phytophthora infestans caused catastrophic failures across Ireland and parts of Scotland, leading to the Great Irish Famine. This crisis signalled the importance of genetic diversity for crop resilience.
Today, institutions such as the International Potato Center in Lima conserve thousands of landrace cultivars. Advances in genetics include the sequencing of the potato genome in 2009, revealing twelve chromosomes and approximately 860 million base pairs. Although earlier theories posited a single highland origin, DNA studies show that most modern cultivars descend from lowland Chilean populations. Additional centres of genetic diversity exist in Mexico, where wild species such as Solanum demissum and Solanum bulbocastanum have provided valuable resistance traits, particularly against late blight.
The significance of the potato to global food security is reflected in the establishment of the United Nations International Day of Potato on 30 May each year, commencing in 2024.

Breeding and Genetic Improvement

Most potato species, including S. tuberosum, exhibit self-incompatibility, preventing effective self-pollination and complicating conventional breeding. Genetic research has identified the mechanisms underlying this trait, and mutations that confer self-compatibility have been incorporated into diploid breeding lines. Crop wild relatives—many of which retain resistance to pests and diseases such as P. infestans—remain essential resources in modern breeding programmes. Their conservation is vital, as much of the natural genetic diversity found within South American wild species is not represented in cultivated varieties.