On August 23, 1969, the US Post Office issued a set of four stamps for the 11th International Botanical Congress (IBC). They were the first US stamps that honored flora from each of the four corners of the United States. They were also the first to include Latin names. Prior to the creation of the IBC, local botanical groups held meetings in their own areas to discuss the natural sciences. Over time, these groups grew large and many called for a large international organization.