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EudicotsMonocots

Stems

Embryos

Roots

One cotyledon Two cotyledons

Leafvenation

Veins usually parallelVeins

usually netlike

Vascular tissuescattered

Vascular tissueusually arranged in ring

Root system usually fibrous (no main root)

Taproot (main root) usually present

PollenPollen grain with

one openingPollen grain withthree openings

Flowers

Floral organs usuallyin multiples of three

Floral organs usually in multiples of four or five

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Apical bud

Shootsystem

Apical bud

TaprootStem

Reproductive shoot (flower)

InternodeNode

Vegetative shoot

BladePetiole

Leaf

Axillary bud

Rootsystem

Lateral(branch)roots

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Storage roots

Pneumatophores

“Strangling” aerial roots4

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Rhizomes

Stolons

Tubers

Rhizome

Stolon

Root

5

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Spines Tendrils

StemStorage leaves

Storage leavesReproductive leaves

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Dermaltissue

Vasculartissue

Groundtissue

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Parenchyma cells withchloroplasts (in Elodea leaf)(LM)

60 m

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Collenchyma cells(in Helianthus stem) (LM) 5 m

9

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Fiber cells (cross section from ash tree) (LM)

25 m

Cell wall

Sclereid cells (in pear) (LM)

5 m

10

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Tracheids and vessels (colorized SEM)

100 mVessel Tracheids

Vessel elements, with perforated end walls

Vessel element

Perforationplate

Pits

Tracheids11

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Sieve-tube element (left)and companion cell:cross section (TEM)

30 m

Sieve plate

Plasmodesma

Sieve-tubeelements

Companioncells

Sieveplate

Sieve plate with pores (LM)

15 m

Sieve-tube elements: longitudinal view (LM)

Nucleus ofcompanioncell

Sieve-tube elements: longitudinal view

3 m

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Shoot tip(shoot apicalmeristem andyoung leaves)

Axillary budmeristem

Root apicalmeristems

Primaryxylem

Cork cambium

Vascular cambium Lateralmeristems

Secondaryxylem

Primaryphloem

Secondaryphloem

Cork cambium

Vascularcambium

Pith

Periderm

Cortex

Primaryxylem

Primaryphloem

Pith

Cortex

Epidermis

Secondary growth in stems

Primary growth in stems

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Internode

This year’s growth(one year old)

Apical budBud scale

Stem

Node

Axillary buds

Last year’s growth(two years old)

Growth of twoyears ago(three years old)

Bud scar

Leaf scar

Leaf scar

Budscar

Leafscar

One-year-oldbranch formedfrom axillary budnear shoot tip

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Corticalcells

GLABRA-2 isnot expressed,and the cellwill developa root hair.

GLABRA-2 is expressed,and the cell remains hairless.

The root cap cells will be sloughedoff before root hairs emerge.

20

m

15

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Mitoticcells

Root cap

Zone of celldivision(includingroot apicalmeristem)

100 m

Zone ofelongation

Zone ofdifferentiation

Vascular cylinder

Root hair

Epidermis

Cortex Dermal

VascularGround

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Core ofparenchyma cells

Vascular cylinder

(b) Root with parenchyma in thecenter (typical of monocots)

Epidermis

Cortex

Dermal

Vascular

Ground

70 m

100 m

Endodermis

Pericycle

Xylem

Phloem 100 m

Endodermis

Pericycle

Xylem

Phloem

(a) Root with xylem and phloem inthe center (typical of eudicots)

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Epidermis

Cortex

Pericycle

Lateral root

Vascularcylinder

Emerginglateralroot

100 m

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Shoot apical meristem

Youngleaf

Leaf primordia

Developingvascularstrand

Axillary budmeristems

0.25 mm19

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Guardcells

Bundle-sheathcell

Sclerenchymafibers

Dermal

VascularGround

(a) Cutaway drawing of leaf tissues

Cuticle

Xylem

Phloem

Stoma

CuticleVein

(c) Cross section of a lilac(Syringa) leaf (LM)

Guard cellsVein Air spaces

(b) Surface view of a spiderwort(Tradescantia) leaf (LM)

Guardcells

Stomatalpore

Epidermalcell

Upperepidermis

Lowerepidermis

Palisademesophyll

Spongymesophyll

10

0

m5

0

m

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Dermal

Vascular

Ground

Groundtissue

Sclerenchyma(fiber cells)

XylemPhloem

Vascular bundles

Epidermis

Cortex

Pith

EpidermisVascular bundle

Ground tissueconnectingpith to cortex

(b) Cross section of stem with scatteredvascular bundles (typical of monocots)

(a) Cross section of stem with vascularbundles forming a ring (typical of eudicots)

1 mm1 mm

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Primaryxylem

Primary phloem

Cortex

Pith

Epidermis

Vascular cambium

(a) Primary and secondary growthin a two-year-old woody stem

Secondaryxylem

Secondary phloem

Growth

Cork

Early wood

Periderm(mainlycorkcambiaand cork)

Primary xylem

Primary phloem

Cortex

Pith

Epidermis

Vascular cambium

Secondaryxylem

Secondary phloem

Vascularray

First cork cambium

Growth

Cork

Layers ofperiderm

Bark

Most recentcork cambium

Secondary xylem

Secondary phloem Vascular

cambium

Corkcambium

Periderm

Vascularray

CorkBark

(b) Cross section of a three-year-old Tilia (linden) stem (LM)

Growthring

Late wood

1.4 mm

1 m

m

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Secondaryxylem

Secondary phloem

Vascular cambium

Growth Vascular cambium

After one yearof growth

After two yearsof growth

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Secondaryxylem

Secondary phloem

Vascular cambium

Growthring

Vascularray

Heartwood

Sapwood

Layers of peridermBark

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