Plant Structure

Plant Tissues A tissue is a group of cells organized to form a functional unit or a structural unit Plants have 3 tissue systems: –Ground tissue (3 types) –Vascular tissue (xylem and phloem) –Dermal tissue (exterior)

Ground tissue found throughout the plant, these tissues perform important functions: –like photosynthesis in the mesophyll tissue –Allows for storage of molecules, like glucose from photosynthesis Provides structural support

Vascular Tissue Allows for transport of food and water throughout the plant Two Types: –Xylem - conducts water and minerals from the roots to the shoots –Phloem - conducts food from the shoots to the roots

Dermal Tissue Epidermis - outermost layer, may contain a cuticle layer

Growth Plant growth occurs at specialized areas called meristem

Specialization of Plant Tissue Root hairs: have the ability to increase the surface area for water.

Cuticle layer: protects the epidermal cells for water loss

Guard cells: allow for the openings called stomata for gas exchange

Xylem and Phloem: allowing for the movement of water and nutrients to all parts of the plant.

Leaves Cuticle is thicker on the top of a leaf than it is on the bottom Stomata - opening controlled by guard cells. More stomata on bottom of leaves Mesophyll- photosynthetic tissue of leaf Xylem and phloem pass through mesophyll (xylem toward the top and phloem toward the bottom)

Mesophyll Palisade layer - cells stacked more closely together, toward the upper epidermis, primary site of photosynthesis Spongy layer - cells more loosely organized, toward lower epidermis, some photosynthesis, but primarily engaged in gas diffusion within the leaf

Leaf function Photosynthesis - more later Transpiration - 99% of water absorbed by plant is lost by transpiration