Keywords: Botanical Congress Lady's-slipper 6c 1969 issue U.S. stamp.jpg en XIth International Botanical Congress - Lady's-slipper Cypripedium reginae - 6-cent 1969 issue U S stamp 1969-08-23 U S Postal Service; National Postal Museum http //arago si edu/category_2034291 html Botanical Congress Issue Bureau of Engraving and Printing Designed by Stanley W Galli other versions PD-USGov Stamps of the United States 1961-1970 Commemorative stamps of the United States Cypripedium on stamps International Botanical Congress US multi-colored stamps |