6 Plant Tissue Types - Copy
Plant Tissue Types
Overview
Plants consist of various tissue types that serve specific roles. Organized groups of cells work together structurally and functionally.
Main Tissue Systems
Dermal Tissue System
Outer covering of the plant (protection).
Interacts with the environment (light, gas exchange).
Ground Tissue System
Responsible for photosynthesis, storage, and support.
Occupies space between dermal and vascular tissues.
Vascular Tissue System
Conducts water and solutes throughout the plant.
Comprises xylem (water transport) and phloem (nutrient transport).
Dermal Tissue System
Acts as the skin layer of all plant organs. Functions include:
Light passage
Gas exchange
Pathogen recognition
Color display
Components of Dermal Tissue
Guard Cells: Regulate the opening and closing of stomata.
Stomata: Pores involved in gas exchange.
Root Epidermal Cells: Enhance water absorption through root hairs.
Ground Tissue Systems
Occupies space between dermal and vascular tissues. Functions:
Photosynthesis: Carried out in the mesophyll of leaves.
Sugar and Starch Storage: Found mainly in roots.
Types of Ground Tissue
Parenchyma: Alive at maturity, performs photosynthesis, and aids in healing. Thin primary cell walls; retains capacity to divide.
Collenchyma: Provides support and flexibility. Unevenly thickened primary cell walls, found in young stems.
Sclerenchyma: Function when dead, provides rigid support. Thickened secondary cell walls; may form fibers or sclerids (e.g., grit in pears).
Vascular Tissue Systems
Responsible for transporting food and water.
Components of Vascular Tissue
Xylem: Conducts water and dissolved minerals. Supports plant structure. Contains tracheids and vessel members.
Phloem: Conducts food and organic substances. Contains companion cells and sieve-tube elements.
Plant Cell Types
Simple tissues are composed of one cell type.
Complex tissues consist of multiple cell types.
Parenchyma Cells
Alive when mature; most common cell type in young plants. Thin-walled; often have large central vacuoles.
Collenchyma Cells
Support and flexibility; have thickened walls at corners. Usually elongated in shape, found in petioles and herbaceous stems.
Sclerenchyma Cells
Dead at maturity; provide structural support. Thickened cell and secondary walls; includes fibers and sclerids.
Special Cork Tissue
Cork Cambium: Produces cork.
Cork contains suberin (a waterproofing fatty lipid). Forms the outer bark of the plant as epidermis dies and falls away. Some unsuberized tissue forms lenticels for gas exchange in bark.