Every organ of the plant has three tissues present.  The outermost tissue is called the Dermal layer.  This is the plant’s ‘skin’ and is mainly a source of protection.  One example of the dermal layer is the bark of a tree.  In leaves, the dermal layer is covered by a waxy cuticle that waterproofs the leaves.  Also present in the dermal layer of the leaves are stomata, or openings, that allow carbon dioxide to enter and complete the Calvin Cycle of photosynthesis.  For more on this, visit my page on Nutrition.

    The innermost layer of a plant is called the vascular tissue.  This is composed of the xylem, phloem and vascular cambium.  The xylem transports water and nutrients absorbed from the roots to the rest of the plant.  The phloem transports energy in the form of glucose and other elements produced by photosynthesis to the rest of the organism.  In trees, the phloem contains sap.  The vascular cambium is a lateral meristem that gives rise to the secondary xylem and phloem.  For more on this, refer to my page on Nutrition

    The intermediate layer is called the ground tissue.  The ground tissue is the layer of tissue that is not a part of the vascular system or the dermal layer.  In leaves, the ground tissue is the mesophyll that contains the photosynthetic cells. 

This is a generic portrayal of a leaf.  Number 3 represents the photosynthetic cells.  Number 6 shows the stomata which are located on the bottom side of most needle-like leaves.  For more on this, visit my page on nutrition.

The stem is the major part of the plant.  The node is an area of branching.  The internode is the area between branching.  A petiole supports leaves and flowers.

This is a diagram showing the major parts of a Tree’s stem.

    Most plants contain three basic members.  These members include the roots, stem, and leaves.  The roots take in water and nutrients from the soil and transport them to the stele for uptake by the xylem for the rest of the organism to use.  In trees, the root system also provides support, especially through the taproot, or main root of the tree.  The stem functions for support and transfer.  In trees, this part of the organism is woody and is called the trunk.  The leaves function to photosynthesize and feed the plant with nutrients.  In conifer trees, the leaves are needle-like and are composed of the blade and petiole.  For more info on this, please refer to my page on Adaptations.