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TISSUESA COLLECTION OF CELLS THAT PERFORM A SPECIFIC FUNCTION
Meristems
Unlike animals, plants have permanent regions of cell division Meristems
Meristems
Apical Meristems Cell division at tips of roots and stems
Produce primary tissue
Meristems
Lateral Meristems Cell division that increases girth of roots and stems
Secondary growth
Lateral Meristems
Vascular cambium Conduction
“Plumbing”
Lateral Meristems
Vascular cambium Cambium
Thin cylinder of brick-shaped cells
Majority of growth contributes to increased girth
Lateral Meristems
Cork cambium Layer of cells outside phloem
layer of vascular cambium
Inside the outer bark
Lateral Meristems
Intercalary Meristems Grassy plants
Develop nodes along stems
Lateral Meristems
Intercalary Meristems Do not contain cork cambium
Vascular bundles
Tissues
Simple Tissues Parenchyma
Collenchyma
Sclerenchyma
Simple Tissue
Parenchyma cells Thin, pliable cell walls
The most abundant of all cell types
Space between parenchyma cells Intercellular space
Simple Tissue
Parenchyma cells that contain numerous chloroplasts Chlorenchyma tissue
Primarily photosynthesis
Parenchyma cells lacking chlorophyll Food and water storage
Soft, edible parts of fruit and vegetables
Simple Tissue
Collenchyma cells thicker and longer Primarily just below the epidermis
Flexible support for growing tissue Strands of celery
Simple Tissue
Sclerenchyma cells thickest and toughest cell walls Impregnated with lignin for support
Simple Tissue
Sclerenchyma cells form two types of tissues Form very hard tissue
Sclereids
Gritty texture of pear
Hard shell of nuts
Simple Tissue
Sclerenchyma cells form two types of tissues Longer tissue that contain a tiny cavity (lumen)
Fibers
Complex Tissue
Composed of two or more types of cells Plumbing tissues
Xylem
Phloem
DICOT
MONOCOT
Complex Tissue
Xylem Conducts water and minerals from the
roots
Transports upward
Complex Tissue
Xylem
Long tubes composed of two tissues Vessels
Large openings at each end allow for water flow
Tracheids
Conduction and support
Smaller cells
Complex Tissue
Xylem
Long tubes composed of two tissues Tracheids
Conduction and support
Smaller cells
Complex Tissue
Xylem
Openings along cell walls connect side by side cells Pits
Lateral flow in trees
Rays
Complex Tissue
Phloem Conduct water and food in both
directions
Primarily down
Complex Tissue
Phloem
Long tubes composed of two tissues Sieve tubes
Similar to xylem vessels
Perforated ends instead of large openings
Sieve plates
Complex Tissue
Phloem
Long tubes composed of two tissues Companion cells
Similar to xylem tracheids
Support sieve cell functions
Complex Tissue
Phloem
Living sieve tube cells contain callose
Injury will result in callose to plug sieve plate Callus plug
Plants seal, not heal
Xylem and Phloem
https://www.youtube.com/watch?v=LQ03xIkLLQU
Complex Tissue
Epidermis Outermost layer of cells
Skin
Complex Tissue
Epidermis
One cell thick (usually)
Multilayered examples Orchid aerial roots
Velamen roots
Complex Tissue
Epidermis Secrete fatty (waxy) substance
Cutin
Protective layer on the outside
Cuticle
Restricts water loss
Resists disease and insects
Complex Tissue
Epidermis Form tubular extensions
Root and foliar hairs
Complex Tissue
Epidermis Openings along surface
Stomata
Gas exchange
Transpiration
Complex Tissue
Epidermis Guard cells
Open and close
Complex Tissue
In woody plants, epidermis sloughed off Periderm
Outer bark
Boxy cork cells
Complex Tissue
Contain fatty substance to waterproof layer Suberin
Protects phloem tissue beneath it
Complex Tissue
Pockets of tissue protruding through periderm Lenticels
Gas exchange
Fig. 4.14
Complex Tissue
Secretory cells Exude nectar, fragrance or oil
Expel waste from cells
Xylem, Phloem, and Transpiration
https://www.youtube.com/watch?v=xGCnuXxbZGk
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