Property:PlantEdible

Indicates the part of a plant that are edible for humans (and other sentients). Valid values are:
 * allows value::Fruit: The plant has edible fruit
 * allows value::Leaves: The leaves of the plant are edible. This is usually the case for Herbs
 * allows value::Root: The roots of the plant are edible (like a potato)
 * allows value::None: Nothing is edible except to particular herbivores