Arabidopsis thaliana is a small flowering plant that is widely used as a model organism in plant biology. Arabidopsis is a member of the mustard (Brassicaceae) family, which includes cultivated species such as cabbage and radish. Arabidopsis is not of major agronomic significance, but it offers important advantages for basic research in genetics and molecular biology.

History of Arabidopsis thaliana
"Arabidopsis thaliana was discovered by Johannes Thal (hence, thaliana) in the Harz mountains in the sixteenth century, though he called it Pilosella siliquosa (and it has gone through a number of name changes since). The earliest report of a mutant (that I know of) was in 1873 (by A. Braun). F. Laibach first summarized the potential of Arabidopsis thaliana as a model organism for genetics in 1943 - he did some work on it much earlier though, publishing its correct chromosome number in 1907. The first collection of induced mutants was made by Laibach's student E. Reinholz. Her thesis was submitted in 1945, the work published in 1947. Langridge played an important role in establishing the properties and utility of the organism for laboratory studies in the 1950s, as did Rédei and others (such as J.H. van der Veen in the Netherlands, J. Veleminsky in Czechoslovakia and G. Röbbelen in Germany) in the 1960s. One of Rédei's many important contributions was to write scholarly reviews on Arabidopsis, a particularly thorough one is in Bibliographica Genetica vol 20, No. 2, 1970, pp. 1- 151. He wrote a more easily found one in Ann. Rev. Genet. (1975) vol. 9,111-127. Both go through some of the early history of the use of Arabidopsis in the laboratory, though the longer 1970 one has all the details." --from Elliot Meyerowitz, 1998