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CHAPTER 5: TISSUES AND THE PRIMARY GROWTH OF STEMS, ribs, skull - Coggle…
CHAPTER 5: TISSUES AND THE PRIMARY GROWTH OF STEMS
External Organization of Stems
Organization
internodes
regions between nodes
leaf axil
just above where leaf attaches
axillary bud
miniature shoot
young leaves
dormant apical meristem
types
vegetative bud
grows into branch
floral bud
grows into flower
bud scales
nodes
where leaves attach
terminal bud
leaf scars
Phyllotaxy
leaf arrangement
Opposite
Whorled
Alternate
Distichous
2 rows
Decussate
4 rows
Spiral
Exploration
vines
stolons
runners
Storage
subterranean
Tubers
horizontal storage
Rhizomes
fleshy, horizontal stems
spread underground
Corms
vertical, thick stems with thin, papery leaves
Bulbs
short shoots with thick, fleshy leaves
Plants and People Grow Differently
animals
determinate growth
precise, invariant form
determinate organogenesis
plants
indeterminate growth
no precise form
indeterminate organogenesis
exceptions
tapeworms have indeterminate growth
annual and biennial plants have determinate growth
Basic Types of Cells and Tissues
Collenchyma
unevenly thick primary wall
thickened corners
plastic support
elongating shoot tips
under epidermis
bands next to vascular bundles
collenchyma is tire
parenchyma is air pressure
#
moderately expensive
Sclerenchyma
primary wall
thick secondary wall
elastic support
do not need "air pressure" like collenchyma
#
cannot grow
types
conducting
vascular cells
mechanical
long fibers
strong and flexible
wood
(strength supports tree and flexibility allows branches to sway in wind but not break)
short sclereids (cuboidal)
brittle and inflexible
shells, pits, stones
prtoects inner fleshy part
often die at maturity
rosettes deposit secondary wall
#
inside primary wall
lignin
areas of plasmodesmata
pits
pit-pair
Parenchyma
thin primary walls
soft parts of plant
active metabolically
alive in maturity
subtypes
chlorenchyma
photosynthesis
chloroplasts
glandular cells
secretion
dictyosomes and ER
transfer cells
short distance transport
extensive plasma membrane
large-scale molecular pumping
aerenchyma
dead parenchyma cells
air pockets
gas exchange and buoyancy
phloem
inexpensive to build
Organs: Replace Them or Reuse Them
differences
plants
vs. animals
Types of organs
three
stems
leaves
roots
many
hearts
brain
liver
kidneys
eyes
etc.
Number
one or two of each
many and many
long it lasts
throws it away and replaces it over and over
lasts entire lifetime
could be fatal if it is damaged
Simple Plants
Liverworts
ribbons or disks of chlorophyllous cells
ribbons with puckered edges
thicker body with ventral and dorsal sides
moderately complex
Mosses
most complex
stem with leaves
no xylem
Hornworts
tiny plants that look like bits of green cellophane
a few cells thick
no epidermis, stomata, collenchyma, sclerenchyma, cortex, pith, xylem, or phloem
ribbon- or disk-shaped sheets of parenchyma cells
least complex
Concepts
plants started growing on land
distinct tissues evolved
parts
leaves
stems
roots
highly modified to environment
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#
#
flowering plants
angiosperms
eudicots
#
broadleaf
asters
maples
roses
monocots
#
grasses
lilies
cattails
palms
basal angiosperms
#
magnolias
laurels
waterlilies
plant types
herbacious
primary plant body
woody
secondary plant body
Parenchyma, Sclerenchyma, and Food
parenchyma
fruits, vegetables
soft and easy to chew
seeds
collenchyma
celery
sclerenchyma
fibers in parenchymatous foods
sclereids
pears
beans
corn
do not digest
Stem Growth and Differentiation
shoot apical meristem
mitotically active
subapical meristem
differentiation
vascular (provascular)
tracheids or vessel elements
protoxylem
extensible
annular and helical secondary walls
#
cells around continue to grow
metaxylem
any secondary wall
#
outer part of vascular bundle
exterior
protophloem
closest to metaxylem
metaphloem
epidermis (protoderm)
#
trichomes
guard cells and stomatal pores
cuticle
ground meristem
cortex
pith
Internal Organization of Stems: Arrangement of Primary Tissues
Cortex
interior to epidermis
photosynthetic parenchyma and sometimes collenchyma
Vascular Tissues
Xylem
conducts water and minerals up from roots
tracheary elements
tracheids
long and narrow
tapered ends
pits
pit pair
pit membrane
lots of friction
vessel elements
short and wide
flat ends
perforation
little friction
stack of vessel
elements forms a vessel
side walls have pits
more evolutionarily recent
flowering plants
maturation
deposits secondary wall
#
cell dies
secondary wall
advantageous in wet conditions
annular thickening
set of rings
not much strength
large surface area for water
helical thickening
1-3 helices
advantageous in dryer conditions
scalariform thickening
extensive, underlies most of primary wall
much more strength
reticulate thickening
net shape
circular bordered pits
secondary wall under virtually entire primary wall
pits to allow water movement
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1 more item...
Phloem
distributes sugars and minerals
sieve elements
sieve tube members
large sieve areas on ends
sieve plates
stack is sieve tube
no nucleus
companion cells
for nuclear control
loading sugars
sieve cells
elongate and spindle shaped
sieve areas distributed along surface
no nucleus
albuminous cells for nuclear control
maturation
only primary walls
remain alive
plasmodesmata
sieve pores
sieve areas
Vascular Bundles
xylem and phloem together
interior to cortex
arrangement
basal angiosperms and eudicots
ring surrounding pith
monocots
"scattered"
collateral
xylem and phloem run parallel to each other
primary xylem
primary phloem
Epidermis
outermost surface
single layer of parenchyma cells
#
functions
water control
cutin
cuticle
wax
stoma
guard cells
water pressure
stomatal pore
barrier
trichomes
hair
dead
protection
alive
secretion
long, narrow epidermal cells
