Plants (Basic Botony)

Plant Organs

• Plant Tissues

  • Meristematic Tissue

    • Groups of undifferentiated, actively dividing cells

    • source of other tissue types

    • produce cells by mitosis

  • Demal Tissue

    • outer covering of plant

    • typically single layer of epidermal cells

    • often covered by waxy cuticle to protect from water loss

  • Vascular Tissue

    • Xylem

      • conducts water

      • consists of narrow tracheids & wide vessel elements

    • Phloem

      • conducts food

      • comsists of siere tube elements & companion cells

  • Ground Tissue

    • located between dermal & vascular tissue

    • Types:

      • parenchyma

        • water storage

      • collenchyma

        • provide support (ex strings of celery)

      • sclerenchyma

        • thick cell walls

Roots

• Root Types

  • Tap Roots

    • central primary root

  • Fibrous

    • branched out

    • uniform in size

• Root Structure tissue types

  • epidermis covered with root hairs to increase surface area

  • end protected by root cap

• Root Funtion

  • anchor the plant

  • aquire water & minerals

    • minerals move by active transport

    • water moves by osmosis from increased mineral concetration inside root

Stems

• Stem Function

  • produce leaves, branches, flowers

  • provide support

  • transport water and food

• Stem Structure

  • nodes

    • where leaves & buds attach

  • internodes

    • space between nodes

• Stem Tissue Arangment

  • monocots

    • vascular bundles scattered throughtout stem

    • xylem faces in, phloem faces out

  • dicots

    • vascular bundles arranged in organized ring, called pith

• Stem Growth

  • Primary Growth

    • increases lenght

    • occurs at apical meristems

  • Secondary Growth

    • increases width

    • occurs in lateral meristems

    • cork cambium is outer covering

    • vascular cambium forms between & produces new xylem & ploem

  • Wood

    • layers of xylem

    • Types of Wood:

      • heartwood—> oldest xylem towards center of stem

      • sapwood—> active in transport

    • old phloem is puched out & breaks down with growth

    • Wood Rings

      • early season growth is light colored xylem

      • later seasons are darker

      • rings indicate tree’s age and enviroment conditions

Leaves

• Leaf Structure

  • Blades

    • flat, collect light

  • Petiole

    • Thin stalk

  • Leaf Shape

    • simple

      • single blade attached to petiole

    • compound

      • multiple leaflets attched to petiole

      • pinnatelt compound

        • leaflets spaced along length of petiole

      • palmately compound

        • leaflets attched at tip of petiole

  • Mesophyll

    • interior cells with chloroplasts

      • carbs produced within move into phloem and carried to rest of plants

    • types:

      • palisade mesophyll

        • outer layer

      • spongy mesophyll

        • loosely connects interior

  • Stomata

    • openings in underside of leaf for gas exchange

  • Guard Cells

    • regulate opening/closing of stomata

      • water pressure within high—>open

      • wate pressure within low—> closed

• Water Transport

  • Evaportation

    • water exiting stomate creates osmotic pressure and pulls water up from roots

  • Capillary Action

    • cohesion/adhesion pulls water up xylem

Flowers

• Flower Function

  • reproductive organs of angiosperms

    • most plants produce both male and female gametophytes

• Flower Components

  • Sepals

    • outermost circle, typically green

    • enclose bud prior to opening

  • Petals

    • inside sepal, bright;y coloreed

  • Stamens

    • male parts which contain:

      • filiment, a thin stalk

      • anther, sac at top of filament

  • Pistil

    • may contain several carpels

    • female part in center which contains:

      • ovary, base where haploid female gametophyte is produced

      • style, thin stalk

      • stigma, where pollen enters

• Pollenation

  • gymnosperms typically wind pollenated

    • produce huge amounts of pollen

  • angiosperms typically animal pollenated

    • very efficient

    • bright colors attract pollenators

    • plants produce necter as a bribe

• Fertilization

  • Steps:

    • Pollen grain lands on stigma

    • pollen tube forms

    • double fertilization occurs

      • nucleus within pollen grain divides to form 2 sperm nuclei

        • one fertilizes with egg to produce zygote

        • other one fertilizes with 2 endosperm nuclei to form 3N cell which forms endospern to nurish seedling

Seeds & Fruit

• Formation:

  • Zygote grows into embryo within seed

  • ovary walls thicken to form fruit

• Dispersal of Seeds

  • the purpose of fuit

  • by animals

    • animals eat fruit & seeds

    • seed coats protect seed in animal digestion tract

    • feces act as fertiizer

  • by water or wind

• Dormancy

  • embryo alive but not growing

  • wait for better growing conditions

• Germination

  • ear;y growth stage of embryo

    • seed absorbs water

    • swells

    • cracks open seed coat

    • root emerges