Plate from 18th century encyclopedia showing the Linnean classes of flowers. There are 24 classes of flowers. Linneaus's classes and orders of plants, according to his Systema Sexuale, were never intended to represent natural groups (as opposed to his ordines naturales in his Philosophia Botanica) but only for use in identification. They were used for that purpose well into the nineteenth century. The classes illustrated are; cryptogamia, decandria, diadelphia, diandria, didyandria, diocecia, dodecandria, enneandria, gynandria, heptandria, hexandria, icosandria, monandria, monodelphia, monoecia, octandria, pentandria, polyandria, polydelphia, polygamia, syngenesia, terandria, tetradynamia, triandria. Within each class there are several orders.