Download Chapter 25 - Jamestown School District

Exploring Plants
Plant Structure & Function
Tissues
 Vascular
tissue form strands that conduct
water, minerals, & nutrients through a
plant
 Dermal tissue  forms protective outer
layer of plant
 Ground tissue  consists of roots, stems,
& leaves
Dermal Tissue
Dermal tissue forms a “skin”  epidermis
 Waxy cuticle that prevents water loss
 Dermal tissue on woody stems & roots is made
up of dead cells  cork
 Dermal tissue also functions in gas exchange

Ground Tissue

Makes up inside of most plants
 Ground tissue in leaves, is made up of
chloroplasts (used for photosynthesis)
 Ground tissue in stems & roots functions in
storage of water, sugar, & starch
 It also surrounds & supports vascular tissue
Vascular Tissue
- 2 types  xylem & phloem
- Both act as plumbing system, carrying
fluids & dissolved substances through a
plant
Xylem
 Thick-walled
cells that conduct water &
mineral nutrients from a plant’s roots,
through stems to its leaves
 Xylem is made up of vessels  allow
water to flow more quickly
Phloem
 Cells
that conduct sugars & nutrients
throughout plant’s body
 Conducting strands in phloem are called
sieve tubes
Plant Transport
QuickTime™ and a
Sorenson Video decompressor
are needed to see this picture.
Roots
 Plants
are anchored down by roots which absorb water and nutrients
 Roots can function in storage of nutrients
 Taproot system  large caproot (carrot)
 Fibrous system  many roots
Roots
 ground tissue surrounding
vascular tissue
 Root Hairs  epidermal cells just behind
root tip - increase surface area to absorb
water and minerals
 Root Cap  mass of cells that covers &
protects actively growing root tip
 Cortex
Stems
 Shoots
of most plants consist of stems &
leaves
 Stems supports the leaves and house the
vascular tissue
 Leaves are attached to stems at points
called nodes
 Space between 2 nodes  internodes
Parts of Plant
QuickTime™ and a
Sorenson Video 3 decompressor
are needed to see this picture.
Nonwoody Stems
plant  plant with stems that
are flexible & usually green
 Stems of herbaceous plants contain
bundles of xylem & phloem  vascular
bundles
 Vascular bundles arranged in ring
 Ground tissue outside ring  cortex
 Ground tissue inside ring  pith
 Herbaceous
Woody Stems
 Trees,
shrubs (pines, oaks, roses, &
hollies) have woody stems
 Woody stems are stiff & non-green
 Buds, which form new growth, are found at
the tips and at the nodes of woody stems
 Heartwood  wood in the center of a
mature stem or tree trunk

Xylem that can no longer conduct water,
provides support
Woody Stems
 outside heartwood, conducts
water with vessel cells
 Sapwood
Leaves
 Primary
photosynthetic organ in plants
 Most leaves have flattened portion 
blade
 Blade attaches to stem by a stalk 
petiole
 Leaf blade may be divided into 2 or more
sections  leaflets
 Stomata- tiny holes that allow gas
exchange to occur in plants
Movement of Water
 Transpiration
 loss of water vapor from a
plant
 More than 90% of water, taken in by roots,
is lost by transpiration
Guard Cells & Transpiration
 Stoma
is surrounded by 2 guard cells
 Changes of water pressure in guard cells
cause the stoma to open or close
 Loss of water from guard cells causes
stomata to close, prevents further water
loss
 Transpiration: loss of water vapor in plants