Vascular plant organs

VASCULAR PLANT ORGANSJJA OBICOInstructor, Dept. of BiologyCAS UP M ilCAS, UP Manila

MERISTEMS

Apical Meristemp

• Shoot Apical MeristemRoot Apical Meristem• Root Apical Meristem

Primary Growthy

• Increase in length of roots and shootsCaused by APICAL MERISTEMS• Caused by APICAL MERISTEMS

• Outcome: PRIMARY PLANT BODY

APICAL MERISTEMS• Give rise to primary meristems• Give rise to primary meristems

Primary meristemsy

• Produces tissues of the primary plant bodyConsists of: Consists of: 1. Protoderm

Primary dermal tissue/ epidermisPrimary dermal tissue/ epidermis2. Procambium

Primary vascular tissuePrimary vascular tissue3. Ground meristem

Ground tissue

Primary meristems Primary tissuesPrimary meristems Primary tissues

ProtodermDermal Tissue

(Epidermis)

Apical Meristem Ground meristem

Ground Tissue

(parenchyma, ll h collenchyma,

sclerenchyma)

Vascular Tissue Procambium

Vascular Tissue

(Primary Xylem and Phloem)

Lateral Meristems

• aka secondary meristemsCauses thickening of the stems and roots • Causes thickening of the stems and roots ▫ SECONDARY GROWTH

Common in eudicots and gymnospermsCommon in eudicots and gymnospermsRare in monocots

• Single-cell layers of meristematic cells that usually form cylinders running lengthwise along

t ta stem or root

L l iLateral meristem• Vascular cambium

C k bi• Cork cambium

- Primary Growth

leafleaf

bladebladeaxillary budaxillary bud

shoot apical meristemshoot apical meristemterminal budterminal bud

Sh t Sh t

bladebladepetiolepetiole

nodenode

vascular tissuevascular tissue

Shoot Shoot systemsystem

vascular tissuevascular tissueinternodeinternode

vascular tissuevascular tissue

root hairroot hairRootRootsystemsystem

dermal tissuedermal tissue

root tiproot tiproot caproot cap

root apical meristemroot apical meristemdermal tissuedermal tissueground tissueground tissuevascular tissuevascular tissue

ROOT• Anchors the plant• Absorbs water and • Absorbs water and

minerals• Root hairs

Patterns of root growthg

• Taproot system▫ Most eudicots gymnosperms▫ Most eudicots, gymnosperms

• Fibrous root systemFibrous root system▫ Seedless vascular plants, monocots▫ Adventitious roots▫ More shallow and horizontal ▫ Common in dry regions

• Zone of cell division▫ Root apical meristem and primary meristemsRoot apical meristem and primary meristems

• Zone of elongation▫ Derivatives stop dividing and begin to grow in

length• Zone of maturation▫ Cells begin specializing in structure and function ▫ Cells begin specializing in structure and function

into different cells types, epidermal cells and conducting cellsR h i▫ Root hairs

External Structures

• Root cap▫ Protects the apical meristem▫ Protects the apical meristem▫ Helps the root penetrate the soil▫ Secretes mucigel- slimy polysaccharide for Secretes mucigel slimy polysaccharide for

lubrication• Root hairs▫ Zone of maturation▫ Where most of absorption of water and mineral

occurs

Tissues of the root

• EpidermisCortex• Cortex

• Endodermis• Stele• Stele▫ Pericycle▫ Vascular TissuesVascular Tissues▫ Pith*

uncutinized epidermis

Root hair

Lateral root

phloemp o

pericycle

Endodermis- with Casparian strip

pericycle

xylem

Cortex- parenchymap y

Casparian stripComposed of suberin-Composed of suberin

Thick cortexExarch- protoxylem devpt.Tetrarch Protostele

• Aerial roots – epiphytesButtress roots flared roots extending from tree • Buttress roots – flared roots extending from tree trunks

• Contractile roots • Contractile roots • Suckers- asexual reproduction• PneumatophoresPneumatophores• Mycorrhiza- absorption of P▫ Endomycorrhizay▫ Ectomycorrhiza

axilTerminal bud

STEMnode

Axillary bud

• Supports leaves or reproductive structures

internode

reproductive structures• Conduct water, minerals

and organic molecules

Protoderm

Ground meristem

Procambium

Meristematic regionMeristematic region

Enlargement regionEnlargement region

ProtodermProtoderm epidermisepidermis

cortexcortex

Ground meristemGround meristemcortexcortex

pithpith

ProcambiumProcambium

phloemphloem

vascular cambiumvascular cambiumProcambiumProcambiumxylemxylem

Tissues of the stem

• Epidermis▫ Cuticle▫ Cuticle▫ Trichomes

• CortexCortex• Vascular Tissues• Pith*Pith

epidermisepidermiscortexcortex

pith raypith ray

pithpithprimary phloemprimary phloem

fascicular fascicular cambiumcambium

i li lprimary xylemprimary xylem

Vascular bundleVascular bundle

SIPHONOSTELE

M t d E di t tMonocot and Eudicot stem

bundle sheathbundle sheath

phloemphloemcompanion cellcompanion cell

sieve tubesieve tube

pitted vesselpitted vessel

Cross section of a monocot stCross section of a monocot stxylemxylem

pitted vesselpitted vessel

annular vesselannular vessel

air spaceair space

vascular bundlvascular bundl

epidermis

tcortex

vascular bundle

pith

Young herbaceous dicot stemYoung herbaceous dicot stemYoung herbaceous dicot stemYoung herbaceous dicot stem

d hd hd hd hendarchendarchendarchendarch

Vascular bundle of a dicot stemVascular bundle of a dicot stem

phloemphloemphloemphloem

Vascular bundle of a dicot stemVascular bundle of a dicot stem

vascular cambiumvascular cambium

phloemphloemphloemphloem

interfascicular cambiuminterfascicular cambiuminterfascicular cambiuminterfascicular cambium

fascicular cambiumfascicular cambium

xylemxylem

Comparison between ROOT and Stem

ROOT STEM

• Protostele • Siphonostele• Protostele• Wider cortex• Uncutinized epidermis

Lack nodes

• Siphonostele• Thinner Cortex• Cutinized epidermis

With nodes• Lack nodes • With nodes

cladode

ModifiedModifiedModifiedModifiedstemsstems

Modified stems: vegetative reproductionModified stems: vegetative reproduction

stoloniferousstoloniferous rhizomatousrhizomatous

CormsBulbs Tubers

Rhizomes Stolon/Runners

LEAF• Main photosynthetic

organ of the plantorgan of the plant• Flat• Transpiration

Leaf buttress

reticulate venation

V PV PVenation PatternsVenation Patternsparallel venation

Phyllotaxy

Leaf shape Leaf shape and and and and

arrangements arrangements have have

Leaf Type

have have environmental environmental significancesignificancesignificancesignificance

Tissues of the leafTissues of the leaf• Epidermis▫ Two surfacesTwo surfaces

Upper- AdaxialLower- Abaxial

▫ With cuticleW t cut c e▫ Stomata▫ Trichomes

• Mesophyll▫ Ground tissue

PalisadePalisadeSpongy

▫ Vascular TissueVein

epidermis

In most plants the epidermis is single layered.In most plants the epidermis is single layered.

epidermisepidermis

Others, as in rubber tree plant, have multiple layers Others, as in rubber tree plant, have multiple layers allowing them to occupy varied selective habitatsallowing them to occupy varied selective habitats

subsidiary cellssubsidiary cells grass-typestoma

dumbell shape

guardguard cellscellsK+K+K+K+KK++ K+K+

HH22OOHH22OOHH22OO HH22OO

CC ti th h th idti th h th idCrossCross--section through the midsection through the mid

upper epidermisupper epidermis xylemxylem

collenchymacollenchyma

phloemphloem

lower epidermislower epidermis

phloemphloem

hhcollenchymacollenchyma

parenchymaparenchyma

Cross section of a leafCross section of a leafcutting through a veincutting through a vein

cuticlestoma

adaxial epidermis

palisade mesophyllp p y

spongy mesophyllveinp gy p y

abaxial epidermisair spacesabaxial epidermis

stoma

L L Leaf modificationLeaf modificationinsectivorous plainsectivorous pla

Venus flytrapVenus flytrap

Nepenthes sp.Nepenthes sp. SarraceniaSarracenia sp.sp.

BRACTBRACT

Succulent

Leaves as homes Leaves as homes for antsfor ants

leaf tendril forleaf tendril forsupportsupport

leaf tendrilfor climbing

leaf tipsleaf tipsfor protectionfor protectionf pf p

The largest leaf is observed in the genus VictoriaVictoriain the genus VictoriaVictoria