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Structure of woody plants (Outer bark # (initiation of cork cambia :check…
Structure of woody plants
Concepts
Derived from meristem
:check:Primary tissue
:<3:Primary plant body
wood and bark
Secondary phloem and cork.
Secondary xylem
additional tissues produced in stems and roots
herbs only those that develops.
:check:Secondary tissue
Roses,oleanders and azaleas
secondary body plant
woody plants.
important consequences.
Rhizomatous
irises bamboo fern
Conducting capacity
helps with overproduction and water loss
adventitious roots
produced to get sugar, water
Conducting tissues
minerals/water,upward cards downard support increases
photosynthetic capacity increases
:red_cross:must grow into adults and reproduce
taller and wider :warning:
disadvantages :no_entry:
expensive energy rich
low germination time.
fight insect, fungi harsh envrionment.
Most donot reproduce for a months
Vascular Cambium :fire:
Initiation of the vascular cambium :red_flag:
near ground
contains both primary and secondary tissues.
In herbaceous species
located b/w metaxylem and metaphloem
become conducting tissues
in woody never undergo cell cyst arrest.
Fusiform initials :checkered_flag:
#
#
thin primary walls
Long, tapered cells 140-462 um on dicots whereas 700-8700 in coniferous
wall parallel
to periclinal wall
continue to fusiform initials
outer daughter cell in cambium , inner is xylem
Ray initials :no_entry:
Different from fusiform
in gymnosperm albuminous cells
storage parenchyma
produce short cells
Arrangement of cambial cells
:star:
occurs in horizontal row
stored cambium
w/o horizontal pattern
non stored cambium.
Secondary Xylem
:pencil2:Types of wood cell
cells on interior of vascular cambium
develop into secondary xtylem
known as wood.
wood may contain :
tracheiods :lock:
vessel elements :<3:
fibers
parenchyma :warning:
Aixial system
contains tracheary elements
radial system
#
hardwoods
of angiosprems and eudicots
strong and tough
soft woods
have few or no fibers
softer consistency
much harder than hardwoods
Growth rings
early wood ring porous
high portion of wide vessels
late wood
summer wood
lower portion of vessels
annual rings
1 years growth
diffuse porous
heartwood and sapwood
heartwood
dark wood
sapwood
lighter, moisture outer region
reaction wood
plant response to stress
in angiosperms it is known as
tension wood.
Secondary phloem
formed from vascular cambium
has an axial and radial system .
has a function of conduction of up and down root/stem.
Outer bark
#
cork and cork cambium :check:
produce cells that turn into phelloderm.
also known as phellogen and cells are cuboidal
cork cell :green_cross:
phellum cell
periderm :no_entry:
layers of cork cells
cork cambium
#
outer bark.
tissues outside innermost cork cambium
inner bark
inner bark
vascular cambium.
innercoat cork cambium
lenticels and oxygen diffusion
:check:
bark becomes permeale to oxygen when cork cambium produces cork cells.
lenticles
region for aerenchymatous cork.
initiation of cork cambia
:check:
may arise in a number of tisuues.
epidermis
cortex
primary phloem
secondary phloem.
timing is variable.
can rise before twig/roots is yr old.
Seconday growth in roots
:check:
A vascular cambium arrises
just like the interfascicular cambium
the new vascular cambium has
same star shape as primary xylem.
some portions of the cambium are pushed outward more rapidly than others.
when a circular cambium is achieved unequal growth stops and all parts grow at similar rates.
Anomalous secondary growth
:check:
unusual primary growth
palm trees
primary tissue consisting of vascular bundles
trunks donot taper at the tips
establishment growth
inscrase in width and addition of adventitious roots in palms
form of primary growth.
Anomalous secondary growth
Secondary growth in monocots.
joshua tree
secondary vascular bundle
columns of parenchyma cells go under cellular division
contain xylem and phelom
alternate cambia produce secondary bodies
that differ from the common type.
roots of sweet potatoes.
amount of storage parenchyma increses.
unequal activity of the vascular cambium.
stems grows in 2 different direction.
remains thin, flat woody ribbon.
as the bauhisnia stem become wider.
conducting capacity increases and remains flexible.
included phloem
types of secondary phloem located between two bands of xylem.
