SYSTEMS IN PLANTS Plants are multicellular organisms with two obvious distinguishing features: –They are usually green –They cannot move from place to.

SYSTEMS IN PLANTS

• Plants are multicellular organisms with two obvious distinguishing features:

– They are usually green

– They cannot move from place to place.

• Flowering plants have two main “body systems:”

the root system and the shoot system.

• These two body systems work together to perform

all of the functions necessary to keep the plant alive:

– exchanging gases with its surroundings

– moving water and nutrients around internally

– reproducing

4.1

Hierarchy of Organization

• The plant has 2 main body systems and

three main types of plant tissue systems.

1. Dermal tissue system – tissues that cover outer surface of the plant

2. Vascular tissue system – tissues responsible for transporting materials within the plant

3. Ground tissue system – all other plant tissues

The Systems

• The root system is typically the part of the plant that grows underground. Its

functions are to anchor the plant, to absorb water and minerals from the soil,

and to store food.

• The shoot system of flowering plants is made up of three parts: the leaf, the

flower, and the stem.

The Leaf

• The leaf is where photosynthesis takes place. Chloroplasts in a plant’s leaves

use carbon dioxide, water, and light energy to produce glucose and oxygen.

light energy + carbon dioxide + water glucose + oxygenchlorophyll

2. The Flower

• Flowers contain male or female reproductive structures. Male reproductive

structures produce pollen grains. Female structures produce eggs. After eggs

are fertilized by pollen, seeds form within a specialized structure called a fruit.

3. The Stem

A plant’s stem supports the plant’s leaves and flowers, and provides a way to

transport the materials the plant needs.

Uses:

People use flowering plant roots, leaves, stems, and flowers (plus the seeds and

fruits that come from them) for food, flavourings, fibres, and medicines.

4.1

PLANT TISSUE SYSTEMS

• Similar to stem cells in animals, meristematic cells are undifferentiated

plant cells that can form any kind of specialized tissue.

• Plant tissues are classified into three tissue systems, each containing a variety

of specialized cell types that carry out specific functions within the plant.

• The three major tissue

systems of plants are

– dermal

– vascular

– ground

4.2

PLANT TISSUE SYSTEMS

• The dermal tissue system forms the outmost layer of a plant. It

includes both epidermal and peridermal tissues. These tissues

are what you see when you look at the leaves, stem, and roots

of a plant.

• Epidermal tissue (epidermis) is the thin layer of cells that covers

the surfaces of leaves, stems, and roots. In woody plants, the

epidermal tissue is replaced by periderm tissue, which forms bark

on stems and large roots.

• Some cells of the dermal tissue system absorb water and minerals from the surrounding

soil. Others produce a layer of wax to waterproof the surface of leaves. Still others

contain chemical irritants for defence.

• A plant’s vascular tissue system is like a network of tubes that reaches from the roots

up the stalk to the leaves. When a plant’s roots absorb water and nutrients from the soil,

the vascular tissue system transports the water and nutrients to the various parts of the

plant, where they are needed for growth.

4.2

epidermal tissue

(epidermis)

periderm tissue

PLANT TISSUE SYSTEMS

• There are two types of vascular tissue: xylem and phloem.

• Xylem carries water and dissolved minerals from the roots to the

rest of the plant. Water moves through the tubes in one direction.

• Phloem transports solutions of sugars produced during

photosynthesis, as well as other dissolved nutrients and hormones.

In phloem tissue food materials may be transported in either direction:

downward from photosynthesizing leaves to stem and roots or upward

from the root and stem to the leaves.

4.2

xylem

phloem

Xylem

• Xylem is a term applied to woody walls of certain cells of plants. Xylem cells tend to conduct water and minerals from roots to leaves.

• Phloem cells conduct food from leaves to rest of the plant. They are alive at maturity and tend to stain green (with the stain fast green). Phloem cells are usually located outside the xylem.

• Cambium in plants is a layer of actively dividing cells between xylem and phloem tissues that is responsible for the secondary growth of stems and roots

Ground tissue cells are part of the third major

tissue of plants.

They are the filler between the dermal and the

vascular tissues.

Ground tissues perform a variety of functions,

depending on their location within the plant:

In the green parts of the plants,

they manufacture nutrients by

photosynthesis.

In the stems, they provide storage and support.

In the roots, they store carbohydrates

Leaves

• All three of these tissues come together in the leaf of a plant.

Dermal

ground

Vascular