Types discussion: Autism (a developmental brain disorder characterized by impaired social interaction and communication skills, and limited range of activities and interests) is the most characteristic and best studied PDD.
A meristem is the tissue in most plants containing undifferentiated cells (meristematic cells), found in zones of the plant where growth can take place. Meristematic cells give rise to various organs of the plant and keep the plant growing.hese secondary meristems are also known as lateral meristems because they are involved in lateral growth. At the meristem summit, there is a small group of slowly dividing cells, which is commonly called the central zone.
While meristem tissue is the source of the regenerative potential of a plant, meristems also play a pivotal role in normal plant growth. Plants have the unique ability to continue to grow and develop new organs while functioning as a mature, reproducing organism. Plants grow larger via cell division and cell elongation. Simple plant growth is facilitated by meristem tissue because it is the primary site of cell division (mitosis) in the plant. Plants develop new organs (stems, leaves, flowers, roots) via cell division and cell differentiation.