Roots, Stems and Leaves  Roots  Absorption  Root hairs increase surface area  Mycorrhizae are symbiotic fungi that help plants absorb nutrients.  Types  Fibrous- shallow, increased surface area(monocots)  Tap – deep, used for storage(dicots)  Adventitious – climbing roots, above ground

Stems  Parts  Nodes  Internodes  Auxillary buds  Terminal buds – apical dominance  Modified Stems  Stolons – above ground horizontal (strawberries)  Rhizomes – below ground horizontal (tubers)

Modified Shoots

Rhizomes

Stolons of Strawberries

Underground Stem

Tubers

Root Hair Radish

Leaves

Plant Tissues  Dermal – epidermis  Protection  Layer of tightly packed cells  Waxy cuticle prevent water loss  Vascular  Xylem – Tracheids and vessel elements  Phloem – sieve tube members and companion cells.  Ground  Between dermal and vascular tissue  Pith and Cortex  Function – photosynthetic, storage and support.  Cortex of a dicot stem- both storage and support(large trees)

Primary and Secondary Walls

Types of Plant Tissues

Parenchymal  Structure  No primary wall  Thin flexible  Least specialized  Large vacuoles  Ground tissue is primarily parenchymal.

Parenchymal Tissue

Collenchymal  Structure  Thicker primary walls than parenchymal cells.  Primary walls have uneven thickness  No secondary wall.  Found in young growing herbaceous plant stem.  Function  To provide flexible support for growing plants

Collencymal Tissue

Sclerencymal Tissue  Structure  Thick secondary wall  Much more rigid than collencymal tissue.  Dead at maturity and cannot elongate  Deposited in tissues of the plant that are not growing.  Found in bark, wood, nut shells, hemp  Makes pears gritty.  Two types of cells – fiber cells and sclereids.  Function  Support

Fiber Cells

Sclereids

Stem Structure

Leaf Anatomy

Behold The Stomata!

Leaf Anatomy

Root Structure

Monocot Root

Dicot Root

Plant Growth

 Plants exhibit indeterminate growth  Grows throughout its entire lifetime.  Annuals, biannuals, perenials Growth Tissue is called Meristematic tissue.  Apical Meristem  Primary growth - vertical growth  Tips of roots and shoots  Lateral Meristem  Secondary growth - horizontal growth  Rings in a tree can determine its age.  Cambiums  Vascular Cambium – xylem and phloem  Cork Cambium – cork and bark  Pericycle –roots and root hairs.

Primary Root Growth

Beware of The Primordial Leaf

Secondary Growth  Most Monocots don NOT exhibet secondary growth.  Vascular Cambium gives rise new vascular tissue  Xylem towards the center of the stem.  Older xylem is towards the center of a tree.  Older xylem is dead  Fills with sap and provides support  Phloem towards the exterior.  Older phloem is closer to the bark.

Cork Cambium  Produces cork to exterior  Primary epidermis splits and falls off  Cork cambium cells secrete a waxy substance called suberin and die.  Cork and cork cambium provide protection and are called the periderm.  Cork cambium does not change diameter.  Old phloem and bark slough off.  Lenitcles are openings in the cork cambium.

Secondary Growth