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EXAM 3 - Coggle Diagram
EXAM 3
Vascularization
Evolutionary perspective
Tracheophytes
synapomorphy
all have vascular tissue
cell type varies
vascular architecture diverse
early evidence
tracheids
annular thickenings
cooksonia
thought to be true tracheids
lycophytes
early vascular group
created towering forests (Carboniferous)
Xylem
no specialized cells
poikilohydric
water content changes w/ moisture in environment
equilibrate water potential through environmental source
water-storage extend
stayed small to reduce water demand
live in perennially wet substrates (stream sides)
more derived homoiohydric
hydroids
bryophytes
water conducting cell
no plasmodesmata (imperforate)
aid in refilling from cavitation
apomorphic trait to true vascular tissue
apomorphic=similar function but different origin
no lignin
tracheary elements
die @ maturity
thickened lignin walls
waterproofing
structural support
Step wise progression
partically thickened
rhynia
vascular tissue not lignified
Lignified tracheids
horneophyton
annular cell wall
helical cell wall
during Devonian
increase in xylem content
increase in tracheid size
increase in tracheid reinforcement
Early tracheids
water transport only (no support)
relatively long & wide
ferns
tracheids + vessel elements in rhizomes of some species
lycophytes
pit membranes
true tracheids
lignified w/ ornamented walls
banded or pitted
evolved likely once
tracheophytes
function in both
water transport
support
tapered @ ends
rather narrow
pine tracheids
function in water movement & support
torus-margo pit membrane
move to prevent cavitation
vessel elements
angiosperms
homogenous pit membrane
large diameter
dead and maturity
open, digested end walls
tracheid v. vessel element
pit membranes absent in perforations of mature vessel elements
conductive area greater in end wall of vessel elements compared to lateral walls
tracheids are similar
perforation plate morphology different than lateral-wall pitting in vessel elements
tracheid endwall similar to lateral
vessel elements diameter > tracheids
vessel elements shorter than tracheids
gymnosperm v. angiosperm
vessels can have greater
max. diameters
max. lengths
vessel elements may be short
but vessel can be much longer
greater conductivity in vessel elements
lowers the cost
construction & transpiration
having vessels permits more fiber
hardwood v. softwood
downside=greater cavitation risk
vessel element differentiation
apical meristem
#
vacuolization
elongation
secondary cell wall
annular
helical
reticulate
porous
dead @ maturity
Phloem
Food conducting cells
widespread in bryophytes
specialized plasmodesmata in end walls
alignment along longitudinal arrays of endoplasmic microtubules
plastids
mitochodria
ER vesicles
breakdown of tonoplast
mix vacuolar & cytoplasmic contents
rarely some species have nuclear breakdown
features common to sieve cells
sieve cells & albuminous cells
transport of
photosynthate
hormones
electric signals
aka Strasburger cells
gymnosperms only these
earlier lineages w/ various types including transtional
= sieve elements
sieve area pores narrow
uniform sieve areas
mostly on ends
lack sieve plate
sieve tube element features
sieve plate
area w/ many sieve pores
usually on end wall
many sieve tube elements together
#
sieve tube
primary cell wall
living protoplasts @ maturity
few organelles (ER)
callose & callose plugs
sieve tube element & companion cell features
transport of
photosynthate
hormones
electric signals
sieve tube element
sieve plate
sieve pore
lateral sieve area
P protein
plastid
smooth ER
mitochondria
companion cell
branched plasmodesmata
vacuole
nucleus
mitochondria
plasmodesmata connections
sieve tube & companion cell from same mother cell
connected by a large quantity of plasmodesmata
1 pore in sieve tube area branched into many on companion cell side
sieve tube contents
P-proteins
may help in plug pres in response to leakage
forisomes
legumes
plug pores
sieve element plastids
mitochondria
very few
endoplasmic reticulum
lost ribosomes
highly folded
phloem differentiation
cell wall thickened
cytoplasmic clearing
no ribosomes
callose deposited around terminal plasmodesmata
nuclear break down
formation of sieve plate & pores
Vascular primary tissue arrangement in shoots :
arrangement changes w/in plant
root & shoot have different arrangements
Monocot
root w/ pith
stem w/out pith
key features to Monocots and Eudicots
eudicot
root w/out pith
stem w/ pith
increasing complexity
complexity increased
stem diameter increased
plant height increased
led to compartmentalization
selected for a woody habit
3 major steele types
protostele
earliest
solid vascular strand
phloem surrounds xylem or interspread
siphonostele
ring of phloem, xylem, surrounding pith
eustele
most complex
strands of phloem & xylem separated by parenchyma
progymnosperms
archs
based on xylem maturation
protoxylem
1st xylem to mature
usually smaller in diameter
metaxylem
develops later
usually larger diameter cells
exarch
protoxylem otside metaxylem
ex. protosteles
endarch
protoxylem in middle
ex. eusteles, atactosteles
mesarch
protoxylem surrounded by metaxylem
ex. siphonosteles
lycophyte
protostele
most ancestral type of stem vasculature
exarch
ferns
siphonostele
xylem surrounded by phloem
endarch
monocotyledonae
atactostele
numerous vascular bundles scattered throughout stem
no pith
vascular bundles often surrounded by sclerenchyma
bundle sheath
eudicotyledonae
eustele
phloem outside xylem
bundles separated by parenchyma
endarch
metaxylem outside protxylem
vascular bundle supported by sclerenchyma
bundle cap
wood
environmental change
amount of water loss/carbon gained increased after Silurian
carboniferous period drained atmosphere of CO2
water demand high
water transport system energetically efficient
minimal maintenance
cell death
transport energy minimal
water filtration close to soil access
selection pressure for wood
increased competition for light selected for
taller plants
more developed tree canopies
higher rates of transpiration
more xylem
wider xylem
longer conduits
likely evolved 5 times
loss of secondary growth
monocotyledonae
arborescent
no secondary growth
1st tree
lepidondrids
carboniferous
~320 mya
vascular cambium only divided internally
archaeopteris
devonian/carboniferous
reproduced via spores
extant lineages
lycophytes
euphyllophyte
secondary growth
complex plant development
growth in girth
produce secondary
xylem (wood)
phloem (inner bark)
ground tissue (rays)
continuous circular ring growth
vascular cambium
fusiform initials
stem cells
xylem & phloem
fascicular cambium
divisions
periclinal
anticlinal
ray initials
stem cells
ray cells
interfascicular cambium
periclinal division
more xylem & phloem
anticlinal division
wider circle of vascular cambium
secondary tissues
secondary xylem
secondary phloem
parenchyma rays
divisions 3D
wood block
unique for each face
longitudinal
transverse
radial
initials
fusiform
longitudinal
ray
radial
annular rings
xylem secondary cell walls robust
phloem is crushed
ring width determined by season & environment
alternation of
early wood
late wood
early v. late
based on season or environment
spring to fall
larger elements to smaller elements
sapwood v. heartwood
sapwood
functions in water transport
heartwood
functions in storage
can no longer transport water
softwood v. hardwood
softwood
tracheids only
little room for fibers
gymnosperms
hardwood
vessel elements' efficiency permit space for fibers
angiosperms
eudicot cross section
ground tissue
rays connect
pith
cortex
vascular tissue
xylem
wood
primary & secondary
phloem
inner bar
secondary
primary squished
lots of fibers
periderm
outer bark
phellem
phellogen
phelloderm
plant armor
periderm
phellem
cork
phellogen
cork cambium
phelloderm
outer bark
inner bark
phloem
cortex
Roots
origins
rhizoid
uni-multicellular projections
anchorage
some w/ mineral uptake
genes
predate land plants
play a role in root hair development
rhizomorphs
lepidodendrates extinct
dichotomous rooting system
lateral stigmarian rootlets
root hairs, mixed reports
highly branched
similar to roots
no chlorophyll
no stomata
develop gravitropically
no root cap
extant species lycophyte
bifurcating
w/ root hairs
no quiescent center
root transition
early w/out root hairs
intact epidermis covered root tip
aniclinal divisions only
devonian lycophyte
independent evolution of
endodermis
root cap
root meristem
diversity of arrangement used ot infer phylogeny
number of initial cells differ
similar genes across plant taxa
root body plan
root types
primary root
derived from radicle
main root
mainly dominant in eudicots
mainly ephemeral in monocots
lateral roots
adventitious roots
derived from stems & leaves
dominant in monocots
#
seminal roots
derived from mesocotyl
general root plan
highly differentiated multicellular axis
found only in sporophytes of vascular plants
functions
anchors plant body to substrate
absorbs water
absorbs dissolved minerals
common features
apical meristem & root
#
pericycle
endodermis
root hairs
cortex
apical meristem
quiescent center
rarely divides
backup plan
maintains initial cells
behind root cap
root cap
evolved independently
lycophyte
euphyllophyte
protect underlying tissues
cells that slough
secrete mucilage
pericycle
pluripotent
initiation of lateral root development
just inside the endodermis
root hairs
single celled
major absorption of water & minerals
via osmosis from hypotonic soil solution to hypertonic
delicate
short lived
cortex
large storage area
outermost layers may show
hypodermis
exodermis
casparian strip
suberized lamella
endodermis
casparian strip
prevents apoplastic movement of water
forces water to move through cell membranes to be filtered
organizational diversity
lycophytes
selaginella sp example
no root cap
no root hairs
monocot
diversity
pith in center
endodermis
surrounded by cortex
details
epidermis
cortex
endodermis
pericycle
xylem
phloem
pith
eudicot
diversity
no pith
endodermis
cortex
details
epidermis
cortex
endodermis
casparian strip
pericycle
xylem
phloem
Leaves
phyllad evolution
initial constraints
high atmospheric global temperatures
low stomatal densities
increase permit greater evaporative cooling
low capacities for water uptake prior to root evolution
lacking efficient vascular transport in leaves
burn up leaf
vascular embolism
polyphyletic origin
earliest evidence of true leaves
lycophytes
microphylls/lycophylls
euphyllophytes
independent evolution
optimal light interception
indeterminate growth proceeded leaf develpment
leaves initiated in regular patterns around stem
optimize light interception for photosynthesis
convergent evolution
leaves had @ least 5 independent origins
liverwort gametophyte
moss gametophyte
lycophyte sporophyte
monilophyte sporophyte
spermatophyte sporophyte
varied leaf development
mitosis of a single cell
liverwort
moss
moss midvein cell layer
microphyll
lycophyte
mitosis of 2 epidermal cells
frond
monilophyte
mitosis of single apical cell
shoot like development
euphylls
seed plants
pool of recruited cells
from flanks of multicellular shoot apical meristem
enation theory
lycophyte leaves
progressive elaboration of epidermal outgrowths
vascular strands entered later
fossils consistent
asteroxylon
living evidence
Selaginella draussiana
2 epidermal cells grow to form leaf pair
zimmerman telome theory
evolution of euphylls
overtopping
unequal branching
primary & side
planation
flattening of axes into 2D
webbing
develop thin tissue between axes of branches
branches becomes veins
webbing becomes mesophyll
by devonian euphylls widespread
phyllad tissues
chlorenchyma
ground tissue
special
contains chloroplasts
main function is photosynthesis
arenchyma
ground tissue
specialized parenchyma
#
contains air spaces from cells being digested
main function permit gas-exchange
large air pockets for buoyancy in aquatic
collenchyma
ground tissue
thickened primary cell walls
main function in flexible
found in bundle sheath of veins in some species
vascular tissue
xylem
tracheids
water transport
phloem
sieve tube element/sieve cells
companion cells/albuminous cells
photosynthate transport
in veins
epidermis
dermal tissue
epidermal cells
guard cells
often cutenized
main function in protecting the internal tissues
phyllad organization
lycophylls
microphyll
single vascular trace along center of blade
vascular strand connects directly to stem
mesophyll
epidermis
stomata
monocot leaf
epidermis
adaxial (outer) & abaxial (towards stem)
covered by cuticle
contains stomata
bulliform cells
helpful for the rolling and unrolling
mesophyll
veins
surrounded by bundle sheaths
eudicot leaf
epidermis
dermal tissue
epidermal cells
guard cells
cuticle
upper & lower
mesophyll
palisade
photosynthesis
spongy
gas exchange
veins
bundle sheath cells
xylem on top phloem on bottom
transportation
water movement
transpiration
moves water from soil to atmosphere
major input of water cycle
water free energy
potential for water to react or move
due to its polarity
attracted to other substances
lower potential when it's surrounded by ions
water potential
based on free energy of water
water moves from less - water potentials to more - water potentials
components
3 components of water potential
ψ = ψp + ψπ + ψm
pressure potential
effect that pressure has on ψ
if water is under pressure, both pressure potential & water potential increases
hydrostatic pressure exerted on water in a cell
in turgid plant cells + value
xylem cells - pressure due to tension
water @ atmospheric pressure has a pressure potential of 0
osmotic potential
effect that solutes have on psi
adding solutes decreases water's free energy, so osmotic potential = always -
difference between the solution & pure solvent resulted after adding solutes
matric potential
adhesion to structures such as cell walls, membranes, & soil particles
adhesion can only decrease water's free energy, so matric potential = always -
adhesion of water molecules to nondissolved structres
ex. soil particles
always -
significant only outside living systems in very dry soils
cohesion-tension theory
theory
transpiration stream
water movement from soil to atmosphere
follows relatively high to low moisture level
from less - to more - water potential
water evaporates out of open stomata to drier atmosphere
creates water potential differential
stomata open shortly after daybreak
close @ times of stress
close @ night
water potential gradient from mesophyll cellls all the way back to xylem draws water from vein
open stomata
water evaporates from intercellular spaces
starts domino effect of water potentials
water enters through root hair via osmosis due to hypotonic soil solution
water moves from hypotonic→hypertonic
root hairs increase surface area
water passes through endodermis, filtering solution, preventing embolism & foreign invaders
casparian strip of root endodermis
forces symplastic movement
embolism=pocket of air
completely makes tracheary element non-functional
water pulled ↑ stem under tension in unbroken column
H2O diffuses out of xylem in leaves, force pulls H2O ↑ through xylem from root hairs
H2O in uppermost tracheary elements must lift weight of entire H2O column
tension is on these molecules
pressure potential = - number
water remains unbroken due to cohesion of water molecules
cohesion due to water polarity
adhesion along cell walls helps to fight gravity
pressure-flow hypothesis
source to sink
transport assimilate from areas where it's made=source
materials moved to sinks
active growing areas
storage areas
assimilate/photosythate loaded into sieve tube elements
w/ help of compaion cells from source
sugars transported as sucrose
actively transported into sieve elements
decreases water potential of STE
increases osmotic concentration
decreases water potential in sieve tube
creates water potential gradient between sieve tube elements & surrounding cells
water enters sieve tube from xylem due to water potential differential
creating turgor pressure
phloem =always close to xylem
xylem = much higher water potential than phloem
water moves from less - to more - water potential
photosyntate moves by bulk flow to
nearest/strongest sink & unloaded
sucrose actively transported from sieve tube
by companion cells
stored as starch
used in metabolims
aerobic respiration
