plantsplants(External & Internal Structures)(External & Internal Structures)

(Part 1)(Part 1)

Shoot Shoot systemsystem

leafleaf

bladebladeaxillary budaxillary bud

petiolepetiolenodenode

vascular tissuevascular tissue

vascular tissuevascular tissue

shoot apical meristemshoot apical meristemterminal budterminal bud

internodeinternode

vascular tissuevascular tissue

root tiproot tip

root hairroot hair

root caproot caproot apical meristemroot apical meristem

RootRoot systemsystem

dermal tissuedermal tissueground tissueground tissuevascular tissuevascular tissue

ROOTSROOTS

Tap root system Fibrous root system

Types of root systemsTypes of root systems

Primary RootPrimary Root

Tertiary RootTertiary Root

Secondary RootSecondary Root

Primary Root SystemPrimary Root System

The primary root is lost and The primary root is lost and is replaced by numerous is replaced by numerous adventitious roots arising adventitious roots arising from the lower part of the from the lower part of the stem. These roots are stem. These roots are fibrous in appearance , that fibrous in appearance , that is, they are slender in form is, they are slender in form and are more or less equally and are more or less equally prominentprominent

Fibrous Root SystemFibrous Root System

Elongation regionElongation region

Meristematic regionMeristematic region

Root capRoot cap

Actively dividing cells in Actively dividing cells in various stages of mitosisvarious stages of mitosis

Produces mucigel for Produces mucigel for protection, lubrication, water protection, lubrication, water and nutrient absorptionand nutrient absorption

Cells in this region increase in Cells in this region increase in size, particularly in lengthsize, particularly in length

The Root The Root TipTip

Quiescent ZoneQuiescent Zone

ProcambiumProcambium

Ground MeristemGround Meristem

ProtodermProtoderm

Three primary meristemsThree primary meristems

outermost primary meristem – outermost primary meristem – gives rise to epidermis.gives rise to epidermis.

gives rise to stele – central gives rise to stele – central cylinder of vascular tissue where cylinder of vascular tissue where xylem and phloem developxylem and phloem develop

store food and uptake of store food and uptake of mineralsminerals

slower or no cell divisionslower or no cell division

phloemphloemvascular cambiumvascular cambiumxylemxylem

epidermisepidermis

cortexcortex

pericyclepericycle

Ground meristemGround meristem

ProcambiumProcambium

ProtodermProtoderm

characterized by the presence of characterized by the presence of root hairsroot hairs

is made up of primary tissues that is made up of primary tissues that develop from transitional develop from transitional meristemsmeristems of the elongation of the elongation regionregion

Maturation regionMaturation region

Increase the surface areaIncrease the surface area for the absorption of waterfor the absorption of water

Root hairsRoot hairs

Young dicot rootYoung dicot root

epidermisepidermis

cortexcortex

vascular cylindervascular cylinder

Exarch - tetrarchExarch - tetrarch

Stele - actinosteleStele - actinostele

cortexcortex

endosperm with endosperm with casparian stripcasparian strippericyclepericycle

xylemxylem

phloemphloem

vascular cambiumvascular cambium

root hairroot hairuncutinized epidermis withuncutinized epidermis with

cortical parenchymacortical parenchyma

endodermis with endodermis with casparian stripcasparian strip

lateral root arising fromlateral root arising from

pericyclepericycle

xylemxylem

phloemphloem

Lateral roots develop from Lateral roots develop from the pericyclethe pericycle

primary rootprimary root

xylemxylem

lateral rootlateral root

epidermisepidermis

cortexcortex

endodermisendodermis

pericyclepericycle

pithpithxylemxylem

phloemphloem

root hairsroot hairs

Monocot rootMonocot root

ExarchExarchpolyarchpolyarch

SteleSteleactinosteleactinostele

Modified Modified RootsRoots

Corn Corn (Zea mays)(Zea mays) Pandan Pandan (Pandanus odoratissimus)(Pandanus odoratissimus)

For Support - Brace rootsFor Support - Brace rootsAerial roots arising from the main stem which penetrates the groundAerial roots arising from the main stem which penetrates the ground

Banyan tree (Banyan tree (Ficus indicaFicus indica)) Mangrove (Mangrove (Rhizophora sp.Rhizophora sp.))

For Support - Prop rootsFor Support - Prop rootsAerial roots arising from the branches which penetrates the groundAerial roots arising from the branches which penetrates the ground

For Support – Clinging rootsFor Support – Clinging roots

English ivy (English ivy (Hedera helixHedera helix) )

Aerial roots which adhere to some kind of supportAerial roots which adhere to some kind of support

For Support - ButtressFor Support - Buttress

Ficus sp.Ficus sp.

Plant-like extensions Plant-like extensions from the lower part of from the lower part of the stemthe stem

Adventitious buds in rootAdventitious buds in root

Bog Yellowcress (Bog Yellowcress (Rorippa palustrisRorippa palustris))

For ReproductionFor Reproduction

For ProtectionFor Protection

Screw pine (Screw pine (Pandanus tectoriusPandanus tectorius))

Presence of spines Presence of spines

Vanda sp.Vanda sp.

For PhotosynthesisFor Photosynthesis

Green aerial rootsGreen aerial roots

enlarged, fleshy and succulent rootsenlarged, fleshy and succulent rootsFor Food StorageFor Food Storage

CarrotCarrot (Daucus carota) (Daucus carota)White RadishWhite Radish (Raphanus sativus) (Raphanus sativus)

development of pneumatophores – development of pneumatophores – roots with spongy tissues protruding roots with spongy tissues protruding

above the groundabove the ground

For AerationFor Aeration

Mangrove (Mangrove (Rhizophora sp.Rhizophora sp.))