SUMMARY
From an examination of 139 varieties of the species Solatium 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 typical 8. andigenum type, to one no less typical of the domestic European varieties commonly known under the specific name of S. tuberosum.
It is suggested that there is, in fact, one, not two, species of cultivated potatoes with the chromosome formula of 2n= 48, and that one is 8. andigenum.
The use of the term S. tuberosum is convenient as indicating the specialization which has overtaken varieties derived from one of the 8. andigenum group forms in Europe, and another in Chiloé and Chile.
That the place of origin of the European potato is to be sought for in the northern extremity of the distribution area of 8. andigenum, and that Colombia is its most likely location.
That 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.