Anomalous secondary growth in Dracena(monocot) stem
Normally secondary growth is absent in monocots. Monocots live for a short period of time and complete its life cycle. Example:jawar, maize, rice etc., But Dracena shows abnormal secondary growth being a monocot stem. Dracena belongs to Lilliaceae family. Formation of Periderm: During secondary growth few peripheral cells of general cortex becomes active and forms Meristem. This acts as Cork cambium or Phellogen. This cork cambium cuts off Cork tissue or Phellem towards outside and secondary cortex or phelloderm towards inside. By this periderm is formed. Formation of cambium: The inner peripheral cells of general cortex becomes meristemetic and forms cambium. Cambium forms parenchyma cells and xylem elements in its inner side. After a short period of time activity changes. Phloem is formed in such a way that phloem is surrounded by xylem. This type of vascular bundles are called Amphiphloic type. In which phloem is surrounded by xylem.