Mendel used Pisum sativum or garden pea in his genetic experiments to explain the principles of genetics. Thomas Hunt Morgan used Drosophila as a model organism in his genetic studies. Hugo Marie de Vries was a Dutch botanist and one of the first geneticists. He is known chiefly for suggesting the concept of genes, rediscovering the laws of heredity in the 1890s while unaware of Gregor Mendel's work, for introducing the term "mutation", and for developing a mutation theory of evolution. He used Oenothera lamarckiana in his studies. Binomial nomenclature was given by Linnaeus. George Bentham and Joseph Dalton Hooker is known for natural classification.