SUMMARY1From an examination of 139 varieties of the speciesSolatium andigenum, it has been possible to establish on the basis of leaf characters six different intergrading groups which show a transition from what is regarded as a typical8. andigenumtype, to one no less typical of the domestic European varieties commonly known under the specific name ofS. tuberosum.2It is suggested that there is, in fact, one, not two, species of cultivated potatoes with the chromosome formula of 2n= 48, and that one is8. andigenum.3The use of the termS. tuberosumis convenient as indicating the specialization which has overtaken varieties derived from one of the8. andigenumgroup forms in Europe, and another in Chiloé and Chile.4That the place of origin of the European potato is to be sought for in the northern extremity of the distribution area of8. andigenum, and that Colombia is its most likely location.5That the potato left some northern port in South America, possibly Cartagena, and that at least one importation reached Spain at the port of Seville not later than 1569