Papaver albiflorum, which is widespread from Eastern Austria and the Czech Republic to Greece and Russia, is available with whitish resp. colorless latex and with yellow latex. Accordingly, some authors distinguish two subspecies: subsp. albiflorum with whitish latex and subsp. austromoravicum with yellow latex. In some areas both colors are said to occur, so this classification is controversial among botanists. In Eastern Austria and the Czech Republic, the latex is said to be yellow. I have not investigated this, because I was surprised by the finding of a white-flowered poppy species, and first had no idea what I was looking at.