Plant cell are totipotent in the sense that the somatic cells have the ability to develop into a complete plant. The evidence was first given by Steward et. al. (1950). They explanted a small piece of phloem of mature carrot and cultured in a liquid medium containing different nutrients and coconut milk. Some embryoids are developed from the tissues, which are further developed into complete plants on the semisolid media. Basing on this principle modern researches are conducted on tissue culture, genetic engineering and biotechnology etc.