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Chapter 7: Roots - Coggle Diagram
Chapter 7: Roots
Other Types of Root and Root Modifications
Mycorrhizae
symbiotic relationship soil fungi in seeded
ectomycorrhizal relationship
fungal hyphae outer cortex cells
endomycorrhizal association
hyphae penetrate cortex root to endodermis
Root Nodules and Nitrogen Fixation
chemical conversion of atmospheric nitrogen to use
bacterium attach convex side into cell by tube
Infection thread
to root inner cortex
undergo mitosis and form root nodule
Contractile Roots
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extend through soil
changes in cortex cells shape
contract slowly
keep at proper depth
seeds germinate @ or near soil
Aerial Roots of Orchids
many epiphytic
live attached tree branches
roots on surface and dangle
root epidermis (velamin)
layers white dead cells
waterproof barrier no leave
Haustorial Roots of Parasitic Flowering Plants
highly modified parisitic plant roots
adhere to host, penetrate
contact host's xylem
photosynthesis
xylem and phloem
little photosynthesis
Prop Roots
stabilize
secondary growth more stable
grow through air then reach ground
buttress roots
upper side grow more than other pts
Roots of Strangler Figs
grow as epiphytes host tree
bird eats fruit
passes onto other tree
root starts survival on rain
travel down trunk
hit soil
branches and takes over
Storage Roots
provide storage for carbohydrates
used for new shoot in spring
perennial have perm shoot
Internal Structure of Roots
Zone of Elongation
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behind root apical meristem
tissues permeable
absorb for root growth
begin to diff visible pattern
no cells mature
outer cells: protoderm
epiderm
center: provascular tissue
primary xylem
primary phloem
in stem
protophloem
protoxylem
closest to meristem
Zone of Maturation/Root Hair Zone
simultaneous processes
root hair grow out
absorb water\mineral
zone of elongat. merges w zone maturat.
cortex cells
transfer from epidermis to vascular tissue
walls / intercellular spaces (apoplastic transport)
matur.
endodermis
casparian strips
passage cells
root pressure
Root Apical Meristem
produce root tissue
cell file
mature root tissue
almost center meristem
quiescent center
form new apical meristem
Mature Portions to the Root
Root Cap
protect root apical meristem
cells closest root meri' are meristematic
constant regeneration
Roots
Anchor plant
producing hormones
absorb water/minerals
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External Structure of Roots
Organization of Root Systems
single taproot
lateral roots (branch roots)
develop from embryonic root, radicle
present in seed
Monocot
fibrous root system
not from pre-existing
adventitious roots
increase absorb and transport
most not do secondary growth
but increase
Eudicot
secondary growth
Structure of Individual Roots
length growth
root tip
longitudal growth
apical meristem
localized growth
root apical meristem
protected by thick layer cells
root cap
dictyosomes secrete complex polysaccharide
mucigel
behind/ zone of elongation
behind/ root hair zone
shoot apical meristem
protected by bud scales/unexp folig leaves
Origin and Development of Lateral Roots
lateral roots
initiated cell division in pericycle
small root primordium
root apical meristem
pushes outward
swell to cortex
epidermis may tear/crush
