Chapter focus u Plant structure and growth u Warning – many terms or vocabulary words u Warning – many diagrams u Focus – structure, function, located.

Chapter focusPlant structure and growthWarning many terms or vocabulary wordsWarning many diagramsFocus structure, function, located next to .

Question ?What heading can be given to the following groups of words?

---------Lettuce PeasBeans----------RhubarbApplesOranges

Question ?What is a vegetable?What is a fruit?

VegetablesLettuceRhubarb

FruitsPeasBeansApplesOranges

PointPlants have organs too, just like animals.Asexual organs (vegetables)Sexual organs (fruits)

Asexual Organs1. Stem2. Leaf3. Root

StemThe main body of the portion above ground of a tree, shrub or herb.The ascending plant axis.

Stem FunctionsSupport of other plant organs.Ps.Storage (water and food).

LeafLateral outgrowths of the stem axis.Primary photosynthetic organs.Function:PhotosynthesisStorage

RootThe descending axis of a plant, normally below ground.Functions:Anchorage.Absorption of water and minerals.Storage.

Sexual Organs1. Flowers2. Fruits3. Seeds

FlowersModified leaves grouped together on a stem.Sexual reproductive organs.Function:Sexual Reproduction

FruitA mature ovary, sometimes including other floral parts.Function:Seed dispersalSeed protection

SeedMature ovule containing the embryo and nutrient tissues.Function:Dispersal unit in sexual reproduction.

Plant Cell TypesDifferentiated by the type and thickness of the cell wall.1. Parenchyma (soft tissue)2. Collenchyma (glue tissue)3. Sclerenchyma (hard tissue)

Parenchyma CellsPrimary wall only.Thin cell wall.Alive when mature, typical" plant cell.

FunctionsPsStorage"Filler" cellsCell division (mitosis)

CollenchymaPrimary wall only.Wall is thickened, especially in the corners.Alive when mature.

FunctionSupport of non-woody plant parts.Ex: veins, stems.

SclerenchymaSecondary wall present.Wall strengthened with lignin.Dead when mature.

Sclerenchyma Types1. Fibers2. Sclereids3. Tracheids4. Vessel Elements

FibersElongated thin cells used for support.Ex: Hemp fibers

SclereidsUsed for hard dense areas and support.Ex: Nut shells, seed coats

TracheidsSpindle - shaped cells with pits in the cell walls.Used for water transportation.VesselFiber

Vessel ElementsWide stocky cells with pits in the side walls; lack end walls.Used for water transportation.

Plant TissuesCan be named by several methods:Ex: Cell Location Cell Origin Cell Function

PointThe same cell can have several tissue names depending on the criteria for naming.

Main Tissue Systems1. Dermal2. Vascular3. Ground

Dermal TissueEpidermis or "skin" of the plant.Often has a cuticle, a waxy coating to prevent water loss.Functions:Prevent water loss.Water absorption (root hairs).

Vascular TissueMade of Xylem and Phloem.Functions:Transport and supportXylem - WaterPhloem - Food

Xylem

Phloem

PhloemSieve Cell alive when functioning, but lacks a nucleus.Companion Cell alive, controls itself and the sieve cell.

Ground TissueTissue between the dermal and the vascular tissues.Functions:"Filler" tissuePsstoragesupport

Question ?How does plant growth and animal growth differ ?

AnimalsWhole organism increases in size.Determinant Growth: grow to a certain size, then stop.

PlantsGrowth in specialized areas only.Indeterminant Growth: grow as long as they live because the specialized areas remain embryonic.

Plant MeristemsPerpetual embryonic regions.Zones for cell division.

Meristem Types1. Apical growth in length. Primary growth.2. Lateral/Cambiums growth in diameter. Secondary growth.

CommentSome tissues like Xylem may be Primary or Secondary depending on which meristem produced the cell.Ex:Primary xylemSecondary xylem

Apical Meristem Types1. RAM Root Apical Meristem: primary growth of roots.2. SAM Shoot Apical Meristem: primary growth of shoots.

RAMLocated at the tip of each growing root.Protected from the soil by the Root Cap.RAM

Root CapProtects RAM.Secrets a polysaccharide lubricant for root growth.

Primary Root Zones1. Cell Division - cells small and embryonic.2. Cell Elongation - cells elongate and start to mature.3. Cell Differentiation - cells mature into final cell types.

Root HairsExtensions of the epidermis to increase surface area for water absorption.Not a true tissue.Comment - root hairs are very delicate and must be continually replaced.

Root Hairs

RAM - Primary Tissues1. Protoderm2. Procambium3. Ground Meristem

ProtodermWill mature into the epidermis and root hairs.

Procambium SteleMatures into the vascular tissues of the stele:XylemPhloemPericycle site of branch roots

Ground MeristemMatures into the ground tissues:Cortex storage tissueEndodermis second skin around the stele that controls the movement of materials into the stele.

EpidermisCortexStele

PericycleXylemPhloemEndodermis

Branch RootsOriginate from the pericycle.Burst their way to the outside.

Root TypesTaproot - one main root.Ex: carrotFibrous Roots - many small roots of equal size.Ex: grass roots

Adventitious RootsRoots that develop from other plant parts.Ex: roots on stem cuttings climbing roots

SAM Produces1. Protoderm2. Procambium3. Ground MeristemComment these tissues mature into the same things as seen in RAM.

SAM DifferencesNo "root" cap.Produces leaves as stem out-growths at the nodes.Has buds.

BudsApical Meristems protected by modified leaves or bud scales.Axillary Buds

Branch StemsDevelop from axillary meristems or axillary buds."External" development.

Modified Stems1. Rhizomes2. Stolons3. Tubers4. Tendrils

RhizomeAn elongated underground horizontal stem.Ex: Iris, many grasses

StolonAn elongated above-ground horizontal stem.Ex: Strawberries Airplane Plant

TuberA much-enlarged, short, fleshy underground stem tip.Ex: Dahlia, Potato

TendrilA slender coiling stem.Ex: Clematis and other climbing vines.

LeavesStem outgrowths for Ps.Leaf Morphology:1. Gross2. Fine

Gross MorphologyBlade - the flattened portion of a leaf.Petiole - stalk of a leaf.

BladePetioleAxillary Buds

Blade/Leaf TypesSimple - 1 blade.Compound - Several blades.

Nodes and InternodesNode - stem area where a leaf and bud are attached.Internode - stem area between nodes.

NodesInternode}

Fine MorphologyThe tissues within a leaf.1. Upper Epidermis2. Mesophyll3. Lower Epidermis4. Veins

Upper EpidermisCuticle present.Usually 1 cell layer thick.Cells w/o chloroplasts .Function: protects the mesophyll.

Mesophyll1. Palisade upright cells.2. Spongy loosely organized cells with air spaces.Function: major sites for Ps.EpidermisEpidermis

Lower EpidermisCuticle present.Usually 1 cell layer.Cells w/o chloroplasts.Stomata present for gas exchange.

Stomata (mouth)Regulated by Guard Cells which have chloroplasts.

Vein StructureXylem: dorsalPhloem: ventralOften surrounded by bundle sheath cells for support.

XylemPhloemBundle Sheath CellsCollenchyma

HomeworkRead Chapter 35, 37No lab broadcast 3/27Chapter 35 Fri. 3/28

Leaf Modifications1. Tendrils: for support Ex: Peas2. Bulbs: for food storage Ex: Onion3. Insect Catching Ex: Carnivorous Plants4. Flowers: thought to be modified leaves.

TendrilsSpinesSucculent LeavesBractsOther Modifications of Leaves

Stem Vascular TissueDicots vascular bundles join together to make a ring. Often have secondary growth.Monocots vascular bundles are scattered. No true secondary growth.

Secondary GrowthGrowth in diameter.Growth from lateral meristems or cambiums.

Cambium Types1. Vascular produces xylem and phloem.2. Cork produces cork.

Vascular CambiumLocation: between primary xylem and phloem.Produces: secondary xylem and phloem.

FibersPhloemVascular CambiumXylemFibers

Vascular Cambium: Cell MaturationInternal xylemExternal phloemThe VC pushes the xylem and phloem apart from each other.

ResultNewest xylem is next to the cambium. Oldest xylem is in the center of stem.

ResultNewest phloem is next to cambium.Oldest phloem is under the epidermis.

ResultXylem accumulates over time. Phloem is destroyed by the outward growth and must be replaced yearly.

Cork CambiumLocation: Cortex (external to the VC).Produces: CorkComment commercial cork is harvested from a Cork Oak.

Cork CellsProduced "outwardly" only.Covered with suberin and are dead when mature.Function insulation and protection.

Vascular CambiumCork CambiumPhloem XylemFibersCortexEpidermis

BarkAll tissues external to the VC.Includes:Phloem (1 degree and 2 degree)Cork CortexEpidermisFiber cells

WoodXylem tissue of a dicot stem.Comment monocots dont have VC and technically dont produce true wood.

Xylem GrowthSpringwood - Large cells Rapid growthSummerwood - Small cells Slow growth

Annual RingsFormed by the growth difference between springwood and summerwood.Usually one produced per year.

CommentRing size varies by climate and growing conditions.Rings can be used to date wooden structures.

Summer WoodSpring WoodOne Years Growth

AngiospermsDivided into two main types:1. Dicotyledons or Dicots2. Monocotyledons or MonocotsCotyledons = seed leaves

Monocots vs. Dicots1. Seeds and embryos2. Leaves3. Stems4. Roots5. Flowers

Seeds and EmbryosDicots - no endosperm. - 2 cotyledons.Monocots - endosperm - 1 cotyledon

LeavesDicots netted veins.Monocots - parallel veins.

StemsDicots - ring pattern - vascular cambiumMonocots - scattered pattern - no vascular cambium

RootsDicots - taproot. - xylem centermost tissue.Monocots - fibrous roots. - pith centermost tissue.

FlowersDicots parts in 4's or 5's.Monocots parts in 3's.

SummaryKnow the main organs of plants and their functions.Know the main cell types or tissues in plants and their functions.

SummaryKnow the structural organization of stems, roots, and leaves.Know the differences between dicots and monocots.