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Roots (Origin and Development of Plants (prop roots (transport (nutrients…
Roots
Origin and Development of Plants
strorage roots
store carbs
long-term
used to produce
new shoot (spring)
prop roots
transport
nutrients and water
contact with soil
secondary growth
strong
no break or sag
buttress rrot
brace trunk
aerial roots of orchids
velamen
root epidermis
waterproof barrier
on tree branches
dangle freely
adapted to drought
contraction roots
buried deep
anchors
mycorrhizae
seed plants + fungi
symbiotic
ectomycorrhizal relationship
fungal hyphae penetrate
outermost root cortex
never invade cell
woody forest plants
endomycorrhizal relationship
herbaceous plants
hyphae penetrate
root cortex
to endordermis
not Casparian strip
Root Nodules and Nitrogen Fixation
nitrogen fixation
conversion N2 to usable compunds
infection thread
bacteria in soil secrete
substance
root hairs curl
#
bacterium attach at
convex side
pushes cell into tube
root nudule
mitosis
bacerium attach
produce N2
Haustorial Roots of Parasistic Flowering Plants
hastoria
parasitic plants
absorb host minerals
Roots of Strangler Figs
birds eat fruits
deposit seeds
seeds germinate
Internal Structure of Roots
root caps
protection
meristematic
root apical meristem
quiescent center
from new meristem
damaged
"healthy cells"
resists
radiation
toxic chemicals
zone of elongation
outermost cells
protoderm
differentiate in to epidermis
Zone of maturation
differentiates into
epidermis
cylinder
altered walls
casparian strips
regulate minerals in xylem
pericycle
between endodermis and vascular tissue
irregular region
lateral roots
mature portions of the root
passage of cells
only casparian strips
absorb minerals
root pressure
absorb minerals
water pressure increases
Other Types of Roots and Root Modifications
lateral roots
intitiated by
cell divisions
#
localized activity
forms
root apical meristem
small root primordium
swells
destroys new lateral root
External Structure of Roots
organization of root structure
leteral roots
developed from
radicle
in seed
largest root
single prominent taproot
taproots
main carbohydrate storage
fibrous root system
mass of roots
similarly size
adventatious roots
not radicles
increase
absorptions
transport capacities
structure of individual roots
rot cap
thick layer cells
protects root apical meristem
mucigel
complex polysaccharide
secreted by dictysomes
Zone of Elongation
behind root cap
cell division and expansion
root hairs
not elonging section
trichome
increase absorption capacity
