powerlecture: chapter 35 plant growth & development
TRANSCRIPT
Success of the AngiospermsSuccess of the Angiosperms
The angiosperms are seed-bearing The angiosperms are seed-bearing vascular plantsvascular plants
In terms of distribution and diversity, they In terms of distribution and diversity, they are the most successful plants on Earthare the most successful plants on Earth
The structure and function of this plant The structure and function of this plant group help explain its successgroup help explain its success
Shoots and RootsShoots and Roots
Shoots Shoots Produce food by photosynthesisProduce food by photosynthesis Carry out reproductive functionsCarry out reproductive functions
Roots Roots Anchor the plantAnchor the plant Penetrate the soil and absorb water and Penetrate the soil and absorb water and
dissolved mineralsdissolved minerals Store foodStore food
Shoot Apical Meristem
primary meristems active
epidermis, ground tissues, primary vascular tissues forming
epidermis, ground tissues, primary vascular tissues
forming
primary meristems
active
Root Apical Meristem
Fig. 29-3a, p.494
Protoderm
Ground meristem
Procambium
epidermis
ground tissues
primary vascular tissues
a The cellular descendants of apical meristems divide, grow, and differentiate. They form three primary meristems, the activity of which lengthens shoots and roots:
Angiosperm Angiosperm Body PlanBody Plan
VASCULAR TISSUES
GROUND TISSUES
SHOOT SYSTEM
ROOT SYSTEM
EPIDERMIS
Ground tissue Ground tissue systemsystem
Vascular tissue Vascular tissue systemsystem
Dermal tissue Dermal tissue system system
Fig. 29-2, p.494
Simple TissuesSimple Tissues
Made up of only one Made up of only one type of celltype of cell
ParenchymaParenchyma
CollenchymaCollenchyma
SclerenchymaSclerenchyma
Parenchyma: A Simple TissueParenchyma: A Simple Tissue
Most of a plant’s soft primary growthMost of a plant’s soft primary growth Pliable, thin walled, many sided cellsPliable, thin walled, many sided cells Cells remain alive at maturity and retain Cells remain alive at maturity and retain
capacity to dividecapacity to divide Mesophyll is a type that contains Mesophyll is a type that contains
chloroplastschloroplasts
stem epidermis
simple and complex tissues inside the stem
parenchymavessel of
xylem phloem
fibers of sclerenchyma
Fig. 29-6, p.496
Collenchyma: A Simple TissueCollenchyma: A Simple Tissue
Specialized for support for primary Specialized for support for primary tissuestissues
Makes stems strong but pliableMakes stems strong but pliable Cells are elongatedCells are elongated Walls thickened with pectinWalls thickened with pectin Alive at maturityAlive at maturity
Sclerenchyma: A Simple TissueSclerenchyma: A Simple Tissue
Supports mature plant partsSupports mature plant parts Protects many seedsProtects many seeds Thick, lignified walls Thick, lignified walls Dead at maturityDead at maturity Two types:Two types:
Fibers: Long, tapered cellsFibers: Long, tapered cells Sclereids: Stubbier cellsSclereids: Stubbier cells
Complex TissuesComplex Tissues
Composed of a mix of cell typesComposed of a mix of cell types
XylemXylem
PhloemPhloem
EpidermisEpidermis
XylemXylem
Conducts water Conducts water
and dissolved and dissolved mineralsminerals
Conducting cells Conducting cells are dead and are dead and hollow at maturityhollow at maturity
vessel membertracheids
Phloem: Phloem: A Complex Vascular TissueA Complex Vascular Tissue
Transports sugars Transports sugars Main conducting Main conducting
cells are sieve-cells are sieve-tube memberstube members
Companion cells Companion cells assist in the assist in the loading of sugarsloading of sugars
sieve plate
sieve-tubemember
companioncell
Epidermis: Epidermis: A Complex Plant TissueA Complex Plant Tissue
Covers and protects plant Covers and protects plant
surfacessurfaces
Secretes a waxy, waterproof Secretes a waxy, waterproof
cuticlecuticle
In plants with secondary growth, In plants with secondary growth,
periderm replaces epidermisperiderm replaces epidermis
MeristemsMeristems
Regions where cell divisions Regions where cell divisions produce plant growthproduce plant growth
Apical meristemsApical meristems Lengthen stems and rootsLengthen stems and roots Responsible for Responsible for primaryprimary growth growth
Lateral meristemsLateral meristems Increase width of stemsIncrease width of stems Responsible for Responsible for secondarysecondary growth growth
Apical Apical MeristemsMeristems
activity atmeristems
new cellselongateand start todifferentiateinto primarytissues
activity atmeristems
new cellselongateand start todifferentiateinto primarytissues
Root apical meristem
Shoot apical meristem
immature leaf
shoot apical meristem
lateral bud forming
vascular tissues
pith
cortex
Fig. 29-10a2, p.498
immature leaf
shoot apical meristem
descendant meristems (orange)
b Sketch of the shoot tip, corresponding to (a) Fig. 29-10b, p.498
Tissue DifferentiationTissue Differentiation
Protoderm Protoderm
Ground meristemGround meristem
ProcambiumProcambium
EpidermisEpidermis
Ground tissueGround tissue
Primary vascular tissuePrimary vascular tissue
Lateral MeristemsLateral Meristems
Increase girth of older roots and stemsIncrease girth of older roots and stems Cylindrical arrays of cellsCylindrical arrays of cells
vascular cambiumcork cambium
thickening
Figure 29.20.aPage 504
Shoot Shoot DevelopmentDevelopment
immature leaf
ground meristem
primary phloem
primary xylempith
procambium
cortex
procambium
protoderm
shoot apical meristem
procambium
epidermis
Figure 29.10 Page 498
immature leaf
shoot apical meristemdescendant meristems (orange)
Stepped Art
Fig. 29-10b-d, p.498
primary phloem
primary xylempith
cortex
Tissue DifferentiationTissue Differentiation
Vascular cambiumVascular cambium
Cork cambiumCork cambium
Secondary vascular tissueSecondary vascular tissue
PeridermPeriderm
Internal Structure of a Internal Structure of a Dicot StemDicot Stem
Outermost layer is epidermisOutermost layer is epidermis Cortex lies beneath epidermisCortex lies beneath epidermis Ring of vascular bundles Ring of vascular bundles
separates the cortex from the separates the cortex from the pith pith
The pith lies in the center of The pith lies in the center of the stemthe stem Figure 29.11.a
Page 499
Internal Internal Structure Structure
of a of a Monocot Monocot
StemStem
• The vascular bundles
are distributed
throughout the ground
tissue
• No division of ground
tissue into cortex and
pith
Figure 29.11.bPage 499
cortex
epidermis
vascular bundle
pith
vessel in xylem
meristem cell
sieve tube in phloem
companion cell in
phloem
Fig. 29-11a, p.499
epidermis
vascular bundle
pith
vessel in xylemcollenchyma
sheath
sieve tube in phloem
companion cell in
phloem
air space
Fig. 29-11b, p.499
Common Leaf FormsCommon Leaf Forms
petiole
blade
axillarybud
node
blade
sheath
node
DICOT MONOCOT
Figure 29.12.a,bPage 500
Adapted for PhotosynthesisAdapted for Photosynthesis
Leaves are usually thin Leaves are usually thin High surface area-to-volume ratio High surface area-to-volume ratio Promotes diffusion of carbon dioxide in, Promotes diffusion of carbon dioxide in,
oxygen outoxygen out
Leaves are arranged to capture sunlightLeaves are arranged to capture sunlight Are held perpendicular to rays of sunAre held perpendicular to rays of sun Arranged so they don’t shade one anotherArranged so they don’t shade one another
POPLAR (Populus)
OAK (Quercus)
MAPLE (Acer)
leaflet
RED BUCKEYE (Aesculus)
BLACK LOCUST (Robina)
HONEY LOCUST (Gleditsia)
Fig. 29-12c,d, p.500
Leaf StructureLeaf Structure
UPPEREPIDERMIS
PALISADEMESOPHYLL
SPONGYMESOPHYLL
LOWEREPIDERMIS
one stoma
cuticle
O2CO2
xylem
phloem
Figure 29.14.bPage 501
leaf blade
leaf vein
stem
Leaf Vein(one vascular bundle) cuticle
Upper Epidermis
Lower Epidermis
Palisade Mesophyll
Spongy Mesophyll
50m
xylem
phloem
cuticle-coated cell of lower epidermis
one stoma (opening across epidermia)
Oxygen and water vapor diffuse out of leaf at stomata.
Carbon dioxide in outside air enters leaf at stomata.
Water, dissolved mineral ions from roots and stems move into leaf vein (blue arrow)
Photosynthetic products (pink arrow) enter vein, will be transported throughout plant body
Fig. 29-14, p.501
Mesophyll:Mesophyll:Photosynthetic TissuePhotosynthetic Tissue
A type of parenchyma tissueA type of parenchyma tissue
Cells have chloroplasts Cells have chloroplasts
Two layers in dicotsTwo layers in dicots Palisade mesophyll Palisade mesophyll
Spongy mesophyll Spongy mesophyll
Leaf Veins: Vascular BundlesLeaf Veins: Vascular Bundles
Xylem and phloem; often Xylem and phloem; often
strengthened with fibers strengthened with fibers
In dicots, veins are netlikeIn dicots, veins are netlike
In monocots, they are parallelIn monocots, they are parallel
Root SystemsRoot Systems
Taproot system of a California poppy
Fibrous root system of a grass plant
Figure 29.19Page 503
Root StructureRoot Structure
Root cap covers tipRoot cap covers tip Apical meristem produces Apical meristem produces
the cap the cap Cell divisions at the apical Cell divisions at the apical
meristem cause the root to meristem cause the root to lengthenlengthen
Farther up, cells Farther up, cells differentiate and maturedifferentiate and mature
Figure 29.16.a
Page 502
Internal Structure of a RootInternal Structure of a Root
Outermost layer is epidermisOutermost layer is epidermis
Root cortex is beneath the epidermisRoot cortex is beneath the epidermis
Endodermis, then pericycle surround Endodermis, then pericycle surround
the vascular cylinderthe vascular cylinder
In some plants, there is a central pithIn some plants, there is a central pith
Fig. 29-18, p.503
Formation of a lateral root
- Originates in the pericycle and grows out through the cortex and epidermis
Function of EndodermisFunction of Endodermis
Ring of cells surrounds vascular cylinderRing of cells surrounds vascular cylinder
Cell walls are waterproof Cell walls are waterproof
Water can only enter vascular cylinder by Water can only enter vascular cylinder by
moving through endodermal cellsmoving through endodermal cells
Allows plant to control inward flowAllows plant to control inward flow
Root Hairs and Lateral RootsRoot Hairs and Lateral Roots
Both increase the surface area Both increase the surface area
of a root systemof a root system
Root hairs are tiny extensions Root hairs are tiny extensions
of epidermal cellsof epidermal cells
Lateral roots arise from the Lateral roots arise from the
pericycle and must push pericycle and must push
through the cortex and through the cortex and
epidermis to reach the soilepidermis to reach the soil
newlateralroot
Secondary GrowthSecondary Growth
Occurs in all gymnosperms, some Occurs in all gymnosperms, some
monocots, and many dicotsmonocots, and many dicots
A ring of vascular cambium produces A ring of vascular cambium produces
secondary xylem and phloemsecondary xylem and phloem
Wood is the accumulation of these Wood is the accumulation of these
secondary tissues, especially xylem secondary tissues, especially xylem
What Happens at What Happens at Vascular Cambium?Vascular Cambium?
Fusiform initials give rise to Fusiform initials give rise to secondary xylem and phloemsecondary xylem and phloem
Ray initials give rise to horizontal Ray initials give rise to horizontal rays of parenchyma rays of parenchyma
primary xylem
primary phloem
VASCULAR CAMBIUM
VASCULAR CAMBIUM
secondary xylem
secondary phloem
stem surface
Fig. 29-20b, p.504
outer surface of stem root
divisiondivision
One of the cells vascular cambium at the start of secondary growth.
One of the two daughter cells differentiates into a xylem cell (coded blue), and the other remains meristatic.
One of the two daughter cells differentiates into a phloem cell (coded pink), and the other remains meristatic.
The same pattern of cell division and differentiation into xylem and phloem cells continues through the growing season.
Fig. 29-20c, p.504
Secondary GrowthSecondary Growth
Figure 29.20.cPage 504
Ongoing cell divisions enlarge the inner core of secondary xylem and displace vascular cambium toward the stem
Formation of BarkFormation of Bark
All tissues outside vascular cambiumAll tissues outside vascular cambium PeridermPeriderm
CorkCork New parenchymaNew parenchyma Cork cambium Cork cambium
Secondary phloemSecondary phloem
periderm (includes cork cambium, cork, new parenchyma)
secondary phloem
BARK
vascular cambium
HEARTWOOD SAPWOOD
Fig. 29-24a, p.507
Annual RingsAnnual Rings
Concentric rings of secondary xylemConcentric rings of secondary xylem Alternating bands of early and late woodAlternating bands of early and late wood Early woodEarly wood
Xylem cells with large diameter, thin wallsXylem cells with large diameter, thin walls Late woodLate wood
Xylem cells with smaller diameter, thicker Xylem cells with smaller diameter, thicker walls walls
1587–1589 1606–1612
Fig. 29-27c, p.509
Annual RingsAnnual Rings Narrow annual rings mark severe drought Narrow annual rings mark severe drought
yearsyears
Types of WoodTypes of Wood
Hardwood (oak, hickory)Hardwood (oak, hickory) Dicot woodDicot wood Xylem composed of vessels, tracheids, and Xylem composed of vessels, tracheids, and
fibersfibers Softwood (pine, redwood)Softwood (pine, redwood)
Gymnosperm woodGymnosperm wood Xylem composed mostly of tracheidsXylem composed mostly of tracheids Grows more quicklyGrows more quickly