A morphological, chemical, and ecological analysis was performed on a large number of collections of Cladonia pyxidata and related taxa from the Netherlands. The following species are recognized: Cladonia fimbriata. Cl. conistea, Cl. conista. Cl. pyxidata. Cl. chlorophaea. Cl. cryplochlorophaea. Cl. merochhrophaea and Cl. grayi. A strain with novochlorophaeic acid is described as a new variety: Cl. merochlrophaea Asah. var. novochlorophaea (colour reactions: P -> orange-red or often negative; K -> negative; C -> negative or yellow; KC -> negative). In morphological and ecological respect a close relationship has been found between 1. Cladonia conistea and Cl. conista, and 2. Cladonia cryplochlorophaea and Cl. merochlorophaea. For comparison also some material from other European countries has been studied.