Cell life and plant tissues

A group of cells with similar structure and job is a tissue; a part of the plant doing one or several jobs is an organ. The term “tissue” was introduced in 1682 by N. Grew. Formative tissue (meristem) has young, rapidly dividing cells: its apical part makes shoots and roots grow longer, while the lateral part (cambium) makes them grow wider, i.e. thicker. Covering tissue protects organs: epidermis (one layer of transparent cells with stomata), cork (dead cells that let neither water nor gas through) and bark. Conducting tissue: xylem (water and salts from root upward) and phloem (organic matter made in leaves, carried down and to other organs). Mechanical tissue (collenchyma, sclerenchyma) gives support. Basic tissue carries out photosynthesis (chlorenchyma) or stores food and water; secretory tissue releases essential oils, resin, nectar and similar substances.