You say potato, I say Solanum tuberosum?

04 February 2011

What do you call a potato? There are plenty of names to choose from. In fact, there are more than 600 scientific names used around the world for just 4 species of cultivated potato. Sorting these out has given scientists a bit of a headache, until now.

An international team have produced a guide to help people make sense of the plethora of potato names. They have published their paper in the Botanical Journal of the Linnean Society.

Material from Europe, the Americas, and Russia was gathered together and analysed by scientists at the N.I. Vavilov Institute of Plant Industry, University of Wisconsin and the Natural History Museum.

The team found that 600 names corresponded to just 4 species of cultivated potato, Solanum ajanhuiri, Solanum curtilobum, Solanum juzepczukii and Solanum tuberosum.

‘It seems odd that such a commonly known plant should have so many names,’ says Museum botanist Dr Sandra Knapp, one of the authors of the paper. ‘But we discovered that through the years, concepts of how to describe and document the incredible variety in this cultivated plant changed.

'Collections where specimens are kept as evidence of these concepts were key to our working out how these names all fit together.'

600 synonyms

The 600 other names were found to be synonyms (where different scientific names refer to the same organism). They are not mistakes, they are just a different view on how to name and classify the incredible diversity of potato types.

Wild potatoes

The team also found that there are about 100 wild species of potato, with about 500 scientific names. Wild species are more genetically diverse than cultivated ones and are likely to hold the key to potato disease resistance.

New potato classification

This research has created a new classification system and means scientists will now be able to communicate more easily in areas such as breeding new potatoes that can withstand climate change and other pressures such as pests and diseases.

Related to the tomato

After rice, wheat and maize, potatoes are the world's most important source of carbohydrate. They belong to the Solanaceae, or nightshade, family of flowering plants. Potatoes are members of the genus Solanum, which has at least 1,000 other species including the aubergine (eggplant) and tomatoes.

Potato origins
A type specimen of the potato Solanum ajanhuiri

Potato species Solanum ajanhuiri. This is a lectotype specimen, which is one of the original specimens used to describe a new species. © N.I. Vavilov Institute of Plant Industry/ Botanical Journal of the Linnean Society

Potatoes are originally from the Andes of South America and they were a staple food of the Incas. Local people still grow an amazing number of different varieties. They were brought to Europe soon after Spanish explorers found them being cultivated in Peru. All of the potatoes cultivated in Europe belong to S. tuberosum, the other 3 species are only cultivated in South America.

Russian collections

Many of the potato names analysed in this research came from Russian collections, including those at the N.I. Vavilov Institute of Plant Industry. The great Russian geneticist Nikolai Vavilov led expeditions in the early 20th century to the Andes and the names given at that time reflected the great variety of potatoes that they found.

For example, the potatoes named Solanum goniocalyx, collected in Peru and Solanum rybinii, collected in Colombia, were both named from plants grown at the institute in 1929 and are now classified as S. tuberosum.

Naming new species

To uncover whether a specimen belongs to one species or another requires an understanding of taxonomy, which is the science of naming, describing and classifying organisms into groups.

The naming of plants follows strict rules laid out in the International Code of Botanical Nomenclature. These rules are one of the oldest examples of a voluntary scientific code.

So, whether it was Solanum goniocalyx in Peru or Solanum rybinii in Colombia, this research means that at least scientists can now be sure they are talking about the same species.

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