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Roots - Coggle Diagram
Roots
Others types of roots and root modifications
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Contractile Roots
more contraction
slow contraction
Mycorrhizae
symbiotic relationship with soil fungi
mycorrhizae
ectomycorrhizal relationship
endomycorrhizal association
substrate another plant body
Aerial Roots of orchids
attached to branches
spread on the surface of bark
hang freely in air
adapted to drought conditions
epidermis is called velamen
several layer of dead cells
waterproof barrier
Root Nodules and Nitrogen Fixation
Nitrogen fixation
chemical conversion
atmospheric nitrogen
to
usable compound
Rhizobium
nitrogen fixation bacteria
infection thread
root nodule
growth limiting factor
Prop Roots
extensive growth
through air
stem of monocot
wider
more vascular bundle
transport additional nutrients
Haustorial Roots of Parasitic Flowering Plants
substrate other plant body
adhere firmly
to their host
parasitic plants
highly modified
haustoria
inadequate growth in soil
Storage Roots
long term storage
for
carbohydrate
produce new shoot
biennial species
2 years lifespan
example
beets, carrots
perennial
permanent organ
root
example
Datura, Phlox
Roots of Strangler Figs
grows as epiphytes
perched on a branch of host tree
do not reach soil
grows at various angles
absorb nutrient form rain water
kills the host tree
branches shades host tree
lack of light for host tree
cannot photosynthesize
Origin and development of the roots
initiated by cell division
in pericycle
some cell
densely cytoplasmic
smaller vacoule
resume mititic activity
root primordium
organizes itself
into
root apical meristem
endodermis
may undergo
cell division
may torn or crushed when
root primordium swells
swells into
cortex
lateral root
emerges to form
root cap
first protoxylem and protophloem elements
begin to differenciate
Internal Structure of Roots
Zone of Elongation
cells expands greatly
just behind the
root apical meristem
permeable tissues
short
actual absorption occurs
Zone of Maturation/ Root hair zone
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root hair grow outward
increases absorption
of
water
minerals
merges gradually
with
zone of maturation
no free access for mineral
to vascular tissue
no distinct boundary
transfer of minerals
from epidermis
to
vascular tissue
Root Apical Meristem
grow in a solution
of
tritiated thymidine
a radioactive precursor of DNA
cells
resistant to harmful agents
quiescent center
mitotically inactive central region
Mature Portion of the Root
builds up root pressure
root hair dies and regenerates
absorption of water reduced
but not stop entirely
passage cells
casparian strips
most important events
at
epidermis
Root Cap
cells
small and meristemic
center portion
for cell formation
to remain in place
provide effective protection
for
root apical meristem
must have
specific structure
growth pattern
constantly regenerating itself
Function of Roots
Absorbing water and minerals
cylindrical shape
higher surface-to-volume ratio
resistant medium
absorptive suface
Producing hormones
shoot growth
integrating growth
two system
cytokinin and gibberellin
Anchoring the plant firmly
to a substrate
provide stability
External Structure of Roots
Structure of individual Roots
growth in length occurs
root elongated
by
localized growth (apical meristem)
only root tip and zone of elongation
must
slide between the soil particle
root apical meristem
located at
apex of root proper
buried under the root cap
protected by thick layer
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mucigel
a complex polysaccharide secrete
by
dicotysomes roots
that helps to moves
root hair
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Organization of Root Systems
enormous absorptive surface
highly branched root system
most seed plant
taproot
larger in size
lateral roots
swollen
highly ramifies set of roots
analogous to the highly branched shoot system
branch roots
develops from
embronic root
radical
fibrous root system
arises when radical dies
more root primordia are initiated
as the plant ages
adventitious roots
increases
absorptive and transport capacities
