Introduction to Tissues and Tissue System
5 Minutes
Plant tissues and tissue systems for students: learn about dermal, ground, and vascular plant tissue types in an English science lesson.
- Dermal, ground, and vascular tissue systems in plants
- Ground tissue cells: parenchyma, collenchyma, and sclerenchyma
- Xylem, phloem, and different types of vascular bundles
What this lesson teaches
Plant tissues are groups of dividing cells that work together to perform specific functions throughout a plant. These tissues are organized into three primary systems known as dermal tissues, ground tissues, and vascular tissues.
Three tissue systems in plants
A cross section of a plant stem reveals three primary layers. The outermost layer is the dermal tissue, which serves as a protective skin or coat for the plant. Just beneath the dermal layer lies the ground tissue, which makes up most of the plant body between the outer covering and the core. At the center sits the vascular tissue system, which moves water and nutrients through specialized conducting pathways.
Dermal and ground tissue functions
- Dermal tissues protect the plant as a soft epidermis in young plants and a tough periderm in older plants, while also forming leaf stomata and hairs on stems and roots.
- Parenchyma cells in the ground tissue carry out photosynthesis and store food for the plant.
- Collenchyma cells provide mechanical support and help damaged areas or cut branches grow back.
- Sclerenchyma cells give structural support and protection across ground structures like the cortex, endodermis, pericycle, and pith.
Vascular tissues and their types
Vascular tissues consist of xylem and phloem cells. Xylem carries water upward from the roots to other parts of the plant, while phloem transports food produced by the leaves to the rest of the plant. Xylem that matures first is called protoxylem, while xylem that matures later is known as metaxylem. In stems, protoxylem lies toward the inside and metaxylem toward the outside in an endarch arrangement, while in roots, metaxylem lies toward the inside and protoxylem toward the outside in an exarch arrangement.
Vascular bundle arrangements
- Radial bundles contain xylem and phloem positioned separately on different radii.
- Conjoint bundles place xylem and phloem together along the same radius.
- Open collateral bundles feature a layer called cambium between the xylem and phloem, whereas closed collateral bundles lack cambium.
- Bicollateral bundles contain a single band of xylem positioned between two layers of phloem.
- Concentric bundles occur when one vascular tissue completely encloses the other in amphivasal or amphicribral forms.