Plant Cells and Tissues

Chapter 23.1

• Plants are composed of cells which contain:– Cell wall– Central vacuole– Chloroplasts

Plant Tissues

• There are four types of tissues in plants:– Dermal tissue– Vascular tissue– Ground tissue– Meristematic tissue

Dermal Tissue• Also called the epidermis

• Composed of flattened cells

• Protects and covers the body of the plant

• Produces the cuticle

Located in the Epidermal Layer…

• Stomata:– Opening in leaf tissue– Help control water loss from plant

• Guard Cells:– Controls the opening/closing of stomata

• Trichomes:– Hairlike projections on stem and leaf– Reduces evaporation of water from plant

Vascular Tissue

• Main function is to transport water, food throughout plant

• Two types of vascular tissue– Xylem– Phloem

Xylem

• Transports water from roots to plant

• Composed of tracheids– Tubular cells tapered

at each end

Phloem

• Transports sugars to all parts of the plant

• Made up of tubular cells joined end to end

Ground Tissue

• In charge of photosynthesis, storage, and secretion

• Found throughout plant

Meristematic Tissue• Produces most of a

plant’s new cells• Located in regions of

actively dividing cells

Roots, Stems, and Leaves

Chapter 23.2

Roots

• Anchor, absorb nutrients, contain vascular tissue to transport materials

• Can be short or long, thick or thin

• Have root hairs– Tiny extensions – Increase surface area of root

Stems• Support leaves and flowers, contains

vascular tissue to transport materials• Arrangement of vascular tissue:

– Monocots: Xylem and phloem scattered throughout stem

– Dicots: Xylem and phloem in a circle that form a ring

Growth of Stem

• Primary growth– Increase in length

• Secondary growth– Increase in diameter

Ex: Woody Stem:

Leaves

• Primary function: Photosynthesis• Some leaves joined directly to stem

– Example: grass blade

• In some leaves, a stalk called a petiole joins the leaf blade to the stem

• Simple leaf– Blade that is not divided

• Compound leaf– Blade divided into leaflets

• Transpiration:– Loss of water through

the stomata

• Leaf venation:– Patterns of veins in the

leaves• Parallel• Pinnate• Palmate

Plant Responses

Chapter 23.3

Plant Hormones

• Plants have hormones that regulate growth and development

• Auxins and Gibberellins (2 hormones) that promote growth in plants

Plant Responses

• Why do stems grow up and roots grow down?

• Tropism– Plant’s response to an external stimulus

• Phototropism– Plant growth toward light

• Gravitropism– Plant growth in response to gravity