German pharmacist and botanist, born in Hamburg. Crueger studied pharmacy in Lüneburg and Hamburg before emigrating to Trinidad in 1841, where he worked as a pharmacist. From 1857 until his death he was employed as a government botanist and director of the botanic gardens Port-of-Spain. During this time he collected specimens in Trinidad, Jamaica, Cuba and Venezuela. Crueger published his Outline of the Flora of Trinidad in 1858 and Orchids and their Morphology in 1864. In 1863 Charles Darwin wrote to Crueger on the subject of orchids, also asking the colonial botanist about the fertilisation of certain Melastomataceae species. Crueger died in San Fernando, Trinidad; his herbarium was left to the botanic garden, though he had also sent specimens to Berlin and Kew.

Sources:
G. Sayre, 1975, "Cryptogamae Exsiccatae: an annotated bibliography of exsiccatae of algae, lichens, hepaticae, and music. V. Unpublished Exsiccatae: I. Collectors", Memoirs of the New York Botanical Garden, 19(3): 307
D.F.L. von Schlechtendal, 1864, Botansiche Zeitung, 22(17): 119-120
I. Urban, 1902, Symbolae Antillanae, 3: 33.