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.
Best Answer: Meristems are tissues within a plant that are undifferentiated-that is, they have no defined identity like being leaf tissue or stem tissue.eristems are the location of growth for plants including the root, base of roots, stems, flowers, and leaves. There are specific names for these types of meristems. For example, root (or shoot or floral) apical meristem and basal meristem. There are two major types of meristems: primary and secondary.