北美地区
The WGSRPD divides the Americas into 7 Northern America and 8 Southern America rather than into the traditional continents of North America and South America. The boundary between Northern America and Southern America was changed from the first edition to the second edition. In the first edition, a south-eastern part of Mexico was included in Southern America, the rest of Mexico being placed in Northern America. This followed the boundary of Mesoamerica in "Flora Mesoamericana". However, it proved unpopular, especially with Mexican botanists, so in the second edition, all of Mexico is placed in Northern America, which thus consists of Mexico, the contiguous United States plus Alaska, Canada, and Greenland, together with associated offshore islands.