PLANT ORGANS AND TRANSPORTATION

ROOTS

Origins

Organizational Diversity

Body Plan

LEAVES

Origins

Tissues

Organization

TRANSPORTATION

Water Movement

Cohesion-tension Theory

Pressure-flow

SEEDS

Origins

Microgametophytes

Ovule Diversity

FLOWERS

Origin

Basic Structure

Structure Modifications

Pollination Syndromes

Traits

Types

Fruits

Dispersal

Seed Dispersal

Rhizoid

anchorage

some with mineral uptake

uni-multicellular projections

Rhizomorphs

dichotomous rooting system

similar to roots

no chlorophyll

no stomata

positive gravitropism

Shoot Turned Root

Rhynie chert, Zosterophyllophyta

Early Devonian

Root Transition

Early without root hairs

Intact epidermis covered root tip.

Devonian lycophyte Asteroxylon mackiei

Anticlinal divisions only

Independent evolution of endodermis and root cap

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Root Types

Primary Root

Lateral Roots

"Main Root"

Dominance?

Mainly dominant in eudicots

Mainly ephemeral in monocots

Derived from radicle

Whats a radicle?

Seminal Roots

Adventitious Roots

Derived from mesocotyl

Derived from stems and leaves

Dominant in monocots

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General Root Plan

Multicellular axis

Highly differentiated

Found only in sporophytes of vascular plants

Features & Functions

Common Features

Functions

Apical meristem & Root cap

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Pericycle

Endodermis

Root hairs

Cortex

Anchor

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Absorption

Absorbs water

Absorbs minerals

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Pluripotent

Inside endodermis

Initiation of lateral root development

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Casparian strip

Filters water by forcing water through cell membranes

Prevents apoplastic movement of water to the center of the root

Symplastic movement through endodermis

Filters foreign molecules. Less likely to form embolisms

Lycophytes

No root cap

No root hairs

Monocot

High diversity

Pith in center

Details

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Eudicot

Also high diversity

No pith

Details

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Phyllad Evolution

Initial Constraints

High atmospheric global temperatures

Selected against leaf formation

Low stomatal densities

Low capacity for water uptake before root evolution

Lack of efficient vascular transport in leaves

vascular embolism

burn up leaf

Polyphyletic origin

Earliest evidence in lycophytes

Independent evolution later in euphyllophytes

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Competition for light interception

Selection pressure for leaf development

Indeterminant growth preceded leaf development

Convergent evolution

5 Independent Origins

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Lycophyte leaves

Enation Theory

Progressive elaboration of epidermal outgrowths

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Euphyll leaves

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Ground Tissue / Specialized Parenchyma

Chlorenchyma

Main Function = Photosynthesis

Aerenchyma

Contains chloroplasts

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Contains air spaces surrounding some cells

Main function = Gas Exchange

Also functions for buoyancy in aquatic plants

Collenchyma

Thickened primary cell walls

Main function = Flexible Support

Found in bundle sheath of veins in some species and along stem edges.

Vascular Tissue

Xylem

Phloem

Dermal Tissue

Epidermis

Main Function = Protecting Internal Tissues

Guard cells

Often cutinized

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Tracheids

Water transport

Lycophylls

Microphylls have single vascular trace

Vascular strand connects directly to stem

Mesophyll, Epidermis, Stomata

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Euphylls

Monocot leaf

Epidermis, Mesophyll, Veins

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Eudicot Leaf

Epidermis, Mesophyll, Veins

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Transpiration

Moves water from soil to atmosphere

Major input of water cycle

Free Energy of Water

Potential for water to react/move due to its polarity

Attracted to other substances

Lower potential when surrounded by ions.

Water potential

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Informational videos

Osmotic Pressure

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Matric Potential

Adhesion of water molecules to nondissolved structures (EX: soil particles)

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How water moves from soil to atmosphere

Follows relatively high to low moisture level

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Water evaporates out of open stomata to drier atmosphere, creating water potential differential

Domino effect of water potentials

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Water enters through root hair via osmosis

Due to hypotonic soil solution

Root hair hypertonic to soil solution

Water passes through endodermis

Water pulled up stem under tension

Water remains unbroken due to cohesion of water molecules

Cohesion due to water's polarity

Photosynthate moves from source to sink

Sources = areas where assimilate is made

Strongest sink = Fruit

Sink = storage area

Assimilate/photosynthate loaded into sieve tube elements w/help of companion cells from source.

Active transport

Sugars transported as sucrose.

Increasing osmotic concentration decreases water potential in sieve tube.

This creates water potential gradient between sieve tube elements and surrounding cells.

Water enters sieve tube from xylem due to water potential differential creating turgor pressure.

Turgor Pressure

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Water move from xylem to phloem.

Photosynthate moved by bulk flow to nearest, strongest sink.

Sucrose actively transported from sieve tube

Used in metabolism or stored as starch.

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Seed Plants:

Seed Ferns (Extinct)

Gymnosperms

Angiosperms

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Earliest Seed

Elkinsia polymorpha

~360 MYA

Late Devonian

Primitive Ovule

Moresnetia zalesskyi

Also ~360 MYA

Lobate Integuments

8-10 lobes fused at chalaza and widely separated

Enclosed Ovule

Complete enclosure of megasporangium within integument

Increases protection from:

Dessication

Herbivory

Example species:

Stamnostoma huttonense

352 MYA

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Ovule Evolution

Evolved from shoot apex

Gymnosperm nucellus apex similar to shoot apex

Genetic similarities

Innovations:

Heterospory

Protection

Integuments

Nucellus

Pollen Capture

Pollen Chamber

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Gymnosperm vs Angiosperm

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Advantages:

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Double Fertilization

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Monocot

Eudicot

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Differences

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Archaefructus sinensis

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Most Primitive Extant

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Perfect, Complete Flower

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male and female parts

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Sepals

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Petals

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Stamen

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Carpels

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Positions

Carpel Position

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Superior ovaries

carpels sit above other organs

Inferior ovaries

carpel below other organs

Imperfect flower

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Display Variation

Infloresence

Taxonomic Importance

Ensure cross pollination :

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Color

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some colors more attractive

requires energy

(omit when possible)

Sometimes in UV spectrum

Smell/Scent

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Scent glands in some species

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Shape

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Symmetry

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Bloom Time

Rewards

Nectar

pollen

oil

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Double Fertilization

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AFTER DOUBLE FERTILIZATION

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Fruit Formation

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Accessory Fruits

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Parthenocarpic fruits

fruit development without fertilization or seed development

Examples include: Bananas, Seedless watermelons, and many more

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Simple Fruits

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Aggregate Fruits

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Multiple Fruits

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Derived from infloresence

Syndromes

Wind

Water

Animal

Self

Passive

Active

Wings, parachutes, lightweight seeds

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Buoyancy

Large airspaces

Example

Coconut

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Hooks catch on fur or hoof

velcro

Gravity

Explosion

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