Mystery of the potato blossoms

When potatoes sprout or otherwise become questionable as to their value for human consumption, they're banished to a certain part of the yard in a sort-of compost pile that isn't the real compost pile. There they usually shoot up ornamental leaves, sometimes followed by blossoms and then by rather good potatoes, very fresh ones. Suddenly the usual blue blossoms have been joined by white ones. Do we have a new kind of potato? It has really been a very long time since we've seriously grown a potato of any kind, so this note is to serve as a reminder to look into this mystery. There seem to be fewer and fewer people who refer to "English peas" (to distinguish them from just plain peas, or "cowpeas" as they're called elsewhere) or "Irish potatoes" (to distinguish them from sweet potatoes or yams). This is akin to needing to order "hot tea" if you don't want iced tea.