Plant Anatomy and Physiology…. Continued

Roots

What do you already know about the root systems?

Roots Purpose: Absorb water and nutrients

from the environment and store energy for the plant.

Ensure the plant is firmly anchored into the ground.

Roots: Structure

The outside of the root is made of epidermal tissue.

Water and nutrients pass through epidermal tissue and enters the plants

Parts: Primary Roots

Meristem

Root Cap

Lateral Roots

Root Hairs

Roots:Primary Roots

Main portion of the root

Includes the section of the root called the zone of elongation

(Rapidly growing section of the root where cells are rapidly dividing through mitosis)

Very bottom of the root tip is called meristem

Hardened portion covering the meristem is called the root cap

Protects the meristem from rocks and other harmful things in the soil

Roots:Lateral Roots

Large branches growing out from the primary root

Roots:Root Hairs Increases the area

of the roots touching the soil, increasing the amount of water and nutrients that can be brought into the plant.

Root Types

Root Types

Fibrous Roots

Taproots

Legumes

Root Types:Fibrous Roots Heavily branched and spread

out roots underground from the stem

Petunias, beans, and peas

Root Types:Taproots System of roots with one large primary root and

few lateral roots

Carrots, radishes and beets

Root Type: Legumes

Plants that have developed an additional use for their roots

Nodules are found on the roots and house special bacteria

Bacteria has the ability to take nitrogen from the environment, that plants cannot use, and convert into a useable form

Often used in rotation with other crops because after harvest, leftover usable nitrogen remains in the soil

Soybeans, alfalfa, peas

Stems

Stems Main trunk of a plant that

gives the plant structure and shape

Supports leaves

Has some ability to make food for the plant

Stem Types Two main types

Herbaceous Stems

Woody Stems

Stem Types:Herbaceous Stems

Found in plants that do not produce wood

Continually grow upward

More flexible and less rigorous than woody stems

Xylem and phloem run together in a bundle

Daisies, grasses, corn, soybeans, tomatoes, potatoes

Stem Types:Woody Stems

Plants that produce wood

Stems constantly grow both upward and outward

Xylem and phloem grow in large rings around the stem

This growth pattern is what creates a tree’s annual rings

Trees and most shrubs

Leaves

Leaves Collects sunlight for the plant to perform

photosynthesis

Controls the plant temperature and evaporation of water from the plant

Leaf Structure

Leaves come in many shapes and sizes

Most leaves have the same type of structure

Veins

Blade

Midrib

Petiole/Leafstalk

Leaf Structure

Internal structure of the leaf is arranged in five layers Cuticle

Upper Epidermis

Palisade Mesophyll

Spongy Mesophyll

Lower Epidermis

Leaf Structure: Cuticle

Top layer of the leaf

Waxy covering

Seals the leaf and prevents leaf from losing water through evaporation

Leaf Structure:Upper Epidermis

Protects the internal parts of the leaf

Seals in water

Leaf Structure:Palisade Mesophyll

Very tightly organized cells

Contains high concentrations of chloroplasts

Structures in the plant cells that collect sun energy and change it into nutrients for the plant

Leaf Structure:Spongy Mesophyll

Loosely arranged cells that allow gases to pass through for use in photosynthesis

Leaf Structure:Lower Epidermis Contains kidney-shaped guard cells

that have openings called stomata

Stoma expand and contract to open and close the leaf

Allows and prevents gases and water from leaving the leaf