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.
The shoot tissues arise from the shoot apical meristem as dermal tissue, ground tissue, and vascular tissue. Secondary meristems (vascular cambium and cork cambium) then add girth to the plant by adding secondary xylem, phloem, and cork.Top of Page. Shoot Apical Meristem: the apical meristem includes the a group of dividing cells that give rise to three primary meristematic tissues, protoderm, ground meristem, and procambium.The outermost layer of cells is the protoderm which forms a single sheet of meristematic cells that give rise to the epidermis.he shoot tissues arise from the shoot apical meristem as dermal tissue, ground tissue, and vascular tissue. Secondary meristems (vascular cambium and cork cambium) then add girth to the plant by adding secondary xylem, phloem, and cork.