PLANTS(External & Internal Structures)

(Part 2)

dermal tissuedermal tissueground tissueground tissuevascular tissuevascular tissue

RootRoot systemsystem

root tiproot tip

vascular tissuevascular tissue

root hairroot hair

root caproot cap

root apical meristemroot apical meristem

Shoot Shoot systemsystem

leafleaf

bladebladeaxillary budaxillary bud

petiolepetiole

nodenode

vascular tissuevascular tissue

shoot apical meristemshoot apical meristemterminal budterminal bud

internodeinternodevascular tissuevascular tissue

The StemThe Stem

Morphology of a

Dicot Stem

nodenode

internodeinternode

leaf scarleaf scar

shoot apical meristemshoot apical meristem

lenticellenticel

bundle scarbundle scar

Shoot apical Shoot apical meristemmeristem

LeafLeaf primordiumprimordium

YoungYoung leafleaf

AxillaryAxillary budbud

Magnified section of the shoot apical meristemMagnified section of the shoot apical meristem

ProcambiumProcambium

Ground meristemGround meristem

ProtodermProtoderm

Enlargement regionEnlargement region

Meristematic regionMeristematic region

epidermisepidermis

cortexcortex

pithpith

phloemphloemvascular cambiumvascular cambium

xylemxylem

Morphology of a

Monocot Stem

o Occur only in monocot (particularly grass) stems at the base of nodes and leaf blades.

o Capable of cell division and allow for rapid growth and regrowth of many monocots.

o Leaf regrowth in grasses evolved in response to damage by grazing herbivores.

Intercalary Meristem

Cross section of a monocot stemCross section of a monocot stem

xylemxylem

phloemphloem

pitted vesselpitted vessel

annular vesselannular vessel

air spaceair space

companion cellcompanion cell

sieve tubesieve tube

bundle sheathbundle sheath

vascular bundlevascular bundle

Cross section of a dicot stem (herbaceous)Cross section of a dicot stem (herbaceous)

phloem fiberphloem fiber

sieve tubesieve tubecompanion cellcompanion cell

xylem parenchymaxylem parenchyma

xylem fiberxylem fiber

phloem parenchymaphloem parenchyma

vascular cambiumvascular cambium

vesselvesseltracheidtracheid

vascular bundlevascular bundle

vascular cambiumvascular cambium

interfascicular cambiuminterfascicular cambium

fascicular cambiumfascicular cambium

xylemxylem

phloemphloemphloemphloem

Vascular bundle of a dicot stemVascular bundle of a dicot stem

Secondary

Growth of

Dicot Stems

pith

Primary xylem

Secondary xylem

Secondary phloem

Primary phloem

Woody dicot stem

Periderm

phellem

phellogen

phelloderm

lenticels

Woody Dicot Stem

Bark

Sapwood

Heartwood

Annual rings

Modified

Roots

Tendrils

For Support

Morning Glory (Ipomea sp.) Squash (Cucurbita sp.)

Twines

For Support

Bougainvillea (Bougainvillea sp.) Hydrangea (Hydrangea petiolaris)

Scramblers (Hooks) Clinging roots at the nodes

Green stem Stick plant (Euphorbia tirucalli) Mimosa (Acacia cyanophylla)

For Photosynthesis

Phylloclades – green, flattened, thin, leaf-like structures

For Protection

Rose (Rosa sp.)

Thorns Onion (Allium cepa)

Enlarged, thickened of fleshy subterranean stem

For Storage

For Reproduction

Strawberry (Fragania sp.)Bermuda grass (Cynodon dactylon)

stolons runners