Meristematic cells demonstrate totipotency most clearly — they are undifferentiated, actively dividing plant cells capable of differentiating into any cell type and regenerating a complete plant. F.C. Steward (1958) demonstrated plant totipotency by regenerating complete carrot plants from single phloem cells. While theoretically all plant cells retain the complete genome and are totipotent, meristematic cells most actively express this potential. Xylem cells are highly differentiated; cork cells are dead.