A collection of cells that perform a specific function TISSUES A 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 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 Develop nodes along stems 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 The most abundant of all cell types 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