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Roots (Other Types of Roots and Root Modifications (Storage Roots…
Roots
Other Types of Roots and Root Modifications
Storage Roots
store carbohydrates
during summer
to use in winter
biennals
beets
carrots
celery
perennials
Dature
Phlox
daisies
roots are only permanent organ
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Prop Roots
growth through the air
palms
screwpines
corn
base grasses
buttress roots
Aerial Roots of Orchids
epiphytic
velamen
waterproof barrier
Contractile Roots
Oxalis
Gladiolus
Crinum
more contraction
cortex cell shape chanegs
keeping stems at proper depth
Mycorrhizae
symbiotic relationship with fungi
ectomycorrhizal relationship
endomycorrihzal association
hyphae branch repeatedly
arbuscule
Root Nodules and Nitrogen Fixation
atomspheric nitrogen
to usable compounds
legumes
Rhizobium
infection thread
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genetic mutations
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Haustorial Roots of Parasitic Flowering Plants
angiosperms
haustoria
attaching to host
Tristerix
inside a cactus
Roots of Strangler Figs
Ficus
epiphytes
grow down the host
reaches soil
grows rapidly
host tree dies
Internal Structure of Roots
Root Cap
cells closest root meristem
meristematic
develop starch grains
sense gravity
settle to lower side of cell
root is growing though
Root Apical Meristem
mature root tissues
quiescent center
mitotically inactive center
no central DNA
can become active
to make new apical mertistem
resistant to harmful agents
radiation
toxic chemicals
Zone of Elongation
behind root apical meristem
cells expand
cells diferenciate
protoderm
ground tissue
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epidermis
provascular tissue
primary xylem
primary pholem
in the stem
protocylem
protophloem
Zone of Maturation/ Root Hair Zone
#
root hairs
increasing absorption
water
minerals
plasmodesmata
endodermis
tangential walls
radial walls
Casparian strips
Mature Portions of the Root
endodermis
layer of suberin
passage cells
slow to develop
root pressure
powerful absorption of water
External Structure of Roots
Organization of Root Systems
highly branched
lateral roots
sweet potatoes
cassava
radicle
#
largest root in system
fiborus root system
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adventitious roots
increase absorption
transport capacities
eudicots never produce
functional
Structure of Individual Roots
simple
no leaves
no leaf scars
root tip
growth in length
localized
root
in solid matrix
apical growth
root cap
dictyosomes
secrete mucigel
protects root apical meristem
shoot apical meristem
protected by bud scales
Zone of Elongation
root hair zone
root hair
increase surface area
extract water from crevices in soil
unicellular
no thick walls
extremely transitory
Origin and Development of Lateral Roots
initiated by the pericycle
localized cell activity
root primordium
swells
breaking endodermis
forms root cap
establishing connection
vascular tissues
parent root
Concepts
Functions
anchoring the plant
provides stability
oriented towards the sun
absorbing water and minerals
sunlight
comes from above
minerals and water
all sides of the root
producing horomones
cytokinin
gibberllin
taproots
storage of food during winter
found in:
carrots
beets
radishes
not functional
