Gravenstein

A triploid apple cultivar that originated in the 17th century or earlier. It requires pollination from other trees, and is a poor pollinator of other apples. The fruit has a tart flavor, and it is heavily used as a cooking apple, especially for apple sauce and apple cider. It does not keep well, and it is available only in season. The skin of the fruit is a delicately waxy yellow-green with crimson spots and reddish lines. Images courtesy of Wikipedia, CC BY-SA 3.0 licensed.