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MODULE VIII: ROOT, ROOT STRUCTURES, modified roots according to their…
MODULE VIII: ROOT
Can grow upwards e.g. mangroves
american ginseng structure has curative powers kung ano itsura ng halaman is yung purpose nila. can cure sterility and anti aging
Roots
have their own connections with one another
, allowing them to supply and provide nutrients as well as share resources.
fungi provide the trees with nutrients and in return they receive sugars
ROOT STRUCTURES
INTERNAL
-Root Cap
The root cap layer closest to the root
meristem is
meristematic.
Maturing cells
detect gravity using
starch grains
Close to the edge of the cap,
the cell’s dictyosomes
secrete mucigel.
The middle lamella
breaks down and releases cells.
Root Apical Meristem
is protected by the root cap.
Roots grow from
Zone of Elongation
Just behind the root cap and root apical
undergo division and expansion.
Zone of Maturation/Root Hair Zone
many of the epidermal cells extend out as narrow
trichomes.
emerge behind the root
hair zone.
Mature Portions of the Root
EXTERNAL
eudicot and monocot have
fibrous root
s
adventitious roots
do not arise f
rom pre-existing lateral roots or the radicle
adventitious roots
however do not come from pre-existing roots
increase absoptive and transport capacities
EUDICOTS undergo secondary growth;increases roots and number of leaves
MONOCOTS cannot undergo secondary growth
modified roots according to their functions
1) anchoring plants to firmly substrate
2)absorbing water and minerals
3)producing
hormones
Gibberellin
required
for plant germination and elongation of internodes.
Cytokinin
counters senescence
, toots vs shoots, and works with ethylene to cause abscission or shedding.
Auxin
allows
photoropism
(plants bending towards light).
Ethylene
ripens fruit
, produced by rapidly growing and dividing cells, allows the roots to grow upwards until it reaches light.
Abscisic Acid
signals dehydration
, makes leaves close their stomata to prevent water loss of plant through phototranspiration.
other root functions
main site of carbohydrate storage in winter
spread horizontally and produce shoots and buds that grows and acts as new plants
some roots grows from trunk and hardens into sharp spines
modified roots that acts as holdfast on rock or brick
parasitic flowering plants use modified roots to get nutrients and water from host.