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
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
General Root Plan
Multicellular axis
Highly differentiated
Found only in sporophytes of vascular plants
Features & Functions
Common Features
Functions
Apical meristem & Root cap
Pericycle
Endodermis
Root hairs
Cortex
Anchor
Absorption
Absorbs water
Absorbs minerals
Pluripotent
Inside endodermis
Initiation of lateral root development
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
Eudicot
Also high diversity
No pith
Details
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
Competition for light interception
Selection pressure for leaf development
Indeterminant growth preceded leaf development
Convergent evolution
5 Independent Origins
Lycophyte leaves
Enation Theory
Progressive elaboration of epidermal outgrowths
Euphyll leaves
Ground Tissue / Specialized Parenchyma
Chlorenchyma
Main Function = Photosynthesis
Aerenchyma
Contains chloroplasts
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
Tracheids
Water transport
Lycophylls
Microphylls have single vascular trace
Vascular strand connects directly to stem
Mesophyll, Epidermis, Stomata
Euphylls
Monocot leaf
Epidermis, Mesophyll, Veins
Eudicot Leaf
Epidermis, Mesophyll, Veins
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
Informational videos
Osmotic Pressure
Matric Potential
Adhesion of water molecules to nondissolved structures (EX: soil particles)
How water moves from soil to atmosphere
Follows relatively high to low moisture level
Water evaporates out of open stomata to drier atmosphere, creating water potential differential
Domino effect of water potentials
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
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.
Seed Plants:
Seed Ferns (Extinct)
Gymnosperms
Angiosperms
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
Ovule Evolution
Evolved from shoot apex
Gymnosperm nucellus apex similar to shoot apex
Genetic similarities
Innovations:
Heterospory
Protection
Integuments
Nucellus
Pollen Capture
Pollen Chamber
Gymnosperm vs Angiosperm
Advantages:
Double Fertilization
Monocot
Eudicot
Differences
Archaefructus sinensis
Most Primitive Extant
Perfect, Complete Flower
male and female parts
Sepals
Petals
Stamen
Carpels
Positions
Carpel Position
Superior ovaries
carpels sit above other organs
Inferior ovaries
carpel below other organs
Imperfect flower
Display Variation
Infloresence
Taxonomic Importance
Ensure cross pollination :
Color
some colors more attractive
requires energy
(omit when possible)
Sometimes in UV spectrum
Smell/Scent
Scent glands in some species
Shape
Symmetry
Bloom Time
Rewards
Nectar
pollen
oil
Double Fertilization
AFTER DOUBLE FERTILIZATION
Fruit Formation
Accessory Fruits
Parthenocarpic fruits
fruit development without fertilization or seed development
Examples include: Bananas, Seedless watermelons, and many more
Simple Fruits
Aggregate Fruits
Multiple Fruits
Derived from infloresence
Syndromes
Wind
Water
Animal
Self
Passive
Active
Wings, parachutes, lightweight seeds
Buoyancy
Large airspaces
Example
Coconut
Hooks catch on fur or hoof
velcro
Gravity
Explosion
