One or more extra chromosomes other than the normal chromosome in the nucleus are called B chromosomes or supplementary chromosomes. B chromosomes are small, non-vital and have heterochromatin. This is sefish genetic material and can be easily distinguished. It contains few genes and does not follow Mendelian pattern. In 1905, Wilson first discovered the B chromosome from the beetle Metapodius. B chromosome is found in 475 species of plants belonging to 163 genera of 42 families. B chromosome is found in organisms such as Ulat Chandal, Bhuta, Brachycome iberidifolia, Lilium callosum, Secale cereale etc.