Transcript Plant Structure and Function

Specialized Tissues in Plants
Plant Organs: Roots, Stems, and Leaves
 Roots
 Anchor the plant and absorb nutrients and water
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Mutualistic relationship with mycorrhizae and rhizobacteria
 Transport Nutrients to the plant
 Store Food
Specialized Tissues in Plants
 Stems
 Support the plant
 Transport water and nutrients
 Protect against predators and disease
Specialized Tissues in Plants
 Leaves
 Conduct photosynthesis
 Increased SA:V with leaf size
 Protect against water loss
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Waxy cuticle
Stomata and Guard Cells
Specialized Tissues in Plants
Plant Tissues: Dermal, Vascular, and Ground Tissue
Specialized Tissues in Plants
 Dermal Tissue
 Covers the plant
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Epidermis (epi = upon) –
 single layer of cells on the outside of the plant
Cuticle – layer of wax that covers the epidermis and prevents
water loss (polarity?)
Trichomes – tiny hairlike projections for protection
Bark – covers the epidermis in woody plants
Root hair cells are found on the epidermis of roots to help
absorb water (SA:V)
Specialized Tissues in Plants
 Vascular Tissue
 Vessels that transport water and nutrients
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Plant “bloodstream”
 Xylem – carries water
 Phloem – carries nutrients
Vascular Tissue - Xylem
 Tracheids – hollow plant cells
of the xylem with thick cell walls
strengthened by lignin
 Lignin resists water and is a
major constituent in wood
 Openings in the cell walls of
tracheids allow water to pass
from cell to cell and therefore
be transported throughout the
plant
 Vessel Elements - hollow
plants cells of xylem stacked end
to end.
 Water passes from cell to cell
through slit-like openings on
the ends of each cell
Vascular Tissue – Phloem
 Sieve Tube Elements – cells
of the phloem that are
arranged end to end and
allow nutrients to flow
throughout the plant in a
watery stream
 Companion Cells – cells of
the phloem that the sieve
tube cells and aid in the
movement of nutrients
Specialized Tissues in Plants
 Ground Tissue
 Produces and Stores food (sugars)
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Composes most of the edible portions of plants
 Contributes to the physical support of the plant
 Ground tissue is composed of three main types of cells
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Parenchyma
Collenchyma
Sclerenchyma
Ground Tissue
 Parenchyma
 Makes up the highest
percentage of ground tissue
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Thin cell walls
Large central vacuole
Limited cytoplasm
 Contain many chloroplasts in
leaves and are the main sight
of photosynthesis
Ground Tissue
 Collenchyma
 Chains of strong, flexible cell walls
 Provide support for plant organs
 Sclerenchyma
 Extremely thick and rigid cells walls
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Found on seed coats (strong!)
Have been used to make rope from hemp
Plant Growth and Meristems
 Meristems – regions of
specialized plant cells in
which mitosis produces new
cells ready for differentiation
 The undifferentiated cells
produced are much like the
stem cells of animals
 Located in parts of plants
that undergo rapid growth
 Allow even the oldest trees to
produce new leaves and new
reproductive organs each
year
 Apical Meristem – located
at the end (apex) of a root or
stem.
 Leads to increase in root or
stem length
 Once produced, the new cells
differentiate into new
dermal, vascular, and ground
tissue
Floral Meristems
 Produce the tissues of
flowers
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Includes the plant’s
reproductive organs as well as
the colorful petals that
surround them