Objectives ! Identify the different types of cells found in
plants and their functions.
! Identify the structures that make up the root system of a plant and their functions.
! Describe the different types of root systems and their advantages.
! Identify the structures that make up the stem of a plant and their functions.
Plant Cells ! Plants contain different
types that have a different function based on their shape.
! Parenchyma Cells are loosely packed cube-shaped cells that store water, conduct photosynthesis, and make up the “fleshy” parts of most plants.
! Collenchyma Cells are have thick, irregular cell walls that provide support.
! Sclerencyma Cells are thick, tightly packed cells that make up hardened parts of plants.
Vascular Tissue ! Vascular tissue is
responsible for moving material from one part of the plant to the other.
! It is found in stems, roots, and leaves.
! Vascular tissue is made up mostly of sclerenchyma cells.
Roots
! Roots anchor plants on one place and absorb nutrients/water from the soil to allow them to grow.
! There are 3 main types of root systems: ! Taproot System ! Fibrous Root System ! Adventitious Root System
Root Systems ! Taproot
Systems consist on one primary or main root with smaller roots that grow from it.
! EXAMPLES: Carrots & radishes
! Fibrous Root Systems consist of many small roots that grow in several directions.
! EXAMPLES: Grasses (most monocots)
! Adventitious Root Systems are specialized roots that grow from stems or leaves to anchor plant in place. ! EXMAPLES: Orchids & Ivy
Parts of a Root ! The inner parts of a roots include:
! Vascular Tissue (Xylem & Phloem) ! Pericycle (Tissue that supports vascular bundle) ! Endodermis (Tissue that surrounds vascular tissue) ! Cortex (Tissue protects vascular tissue) ! Epidermis (Outer most tissue) ! Root Hairs (OUTER: Increase surface area and reach)
Stems ! Stems provide support
and materials to the leaves, flowers, fruits/ vegetables, and all other parts of the plant.
! The outer parts of a stem are: ! Nodes (Where leaves
grow out.) ! Internodes (Space
between nodes) ! Lateral Buds (where a
new shot will form.) ! Terminal Bud (End of
stem.)
Monocot/Dicot Stems ! The inner parts of a stem include:
! Vascular Bundles (Xylem & Phloem) ! Ground tissue (Monocot)/Pith (Dicot) ! Cortex (Dicot only) ! Epidermis
Secondary Growth of Stems ! Herbaceous stems are soft and usually
represent one season’s growth. ! Woody stems consist of hardened,
woody tissue that moves to the outside of the plant, while new tissue forms on the inside.
! Woody stems consist of several layers, and can be used to determine the age of a plant.
Woody Stems ! Woody plants grow
differently by season creating rings. Each ring consists of: ! Springwood (Lots of
Xylem because of water.)
! Summerwood (Little Xylem due to lack of water.)
! Woody stems consist of: ! Heartwood (Growth) ! Sapwood (Cork) ! Bark (Not all)
Springwood Summerwood Annual Ring