Limestone

Limestone areas usually make excellent farmland because of the nutrients liberated by decomposition of the rock. On limestone slopes in eastern United States the yellow lady's slipper is fairly common. It has a wide distribution, but is now rare in western Europe owing to the destruction of forests and excessive picking. The purple-flowered showy orchids inhabits rich woods (not necessarily limestone), and extends just across the Canadian border.

The soil profile of the limestone slopes consists entirely of a loose, rich humus.