Transcript Plant Anatomy

Plant Anatomy

Root
◦ Anchors plant in place and
provides nutrition
◦ Want high SA/V Ratio

Shoot (stem)
◦ Consists of stems, leaves,
and flowers
◦ Leaves attached at nodes
◦ Internodes: areas between
nodes
Basic Plant Anatomy

Roots anchor plant in soil, absorb
minerals & water, & store food
1
◦ fibrous roots (1)
 mat of thin roots that spread out
 monocots
◦ tap roots (2)
 1 large vertical root
 Accompanied by less-prominent
lateral roots
 Nutrient storage organ (carrots)
 dicots
◦ Adventitious roots
 Arise above ground from points along the
stem
Roots
2

shoots (stems)
◦ nodes
 Internodes
◦ buds: embryonic
shoots
 apical buds: at tip
of each
stem/branch
◦ Upward & outward
growth
 Lateral buds:
where leaves meet
stems
 flower buds &
flowers
Shoots
stolons (strawberries)
tuber (potato)
Modified shoots
rhizome (ginger)
bulb (onion)
Leaves

Function of leaves
◦ photosynthesis
 energy production
 C6H12O6 production
◦ gas exchange
◦ transpiration
simple vs. compound
tendrils (peas)
spines (cacti)
succulent leaves colored leaves (poinsetta)
Modified leaves



Stomata
Stomata: openings
in epidermis of leaf
that allow gas
exchange between
the inside of the
leaf and the
external
environment
Stomates/Stoma
Operated by guard
cells
Stomata

Both systems
depend on the other
◦ roots depend on
sugars produced by
photosynthetic
leaves
◦ shoots depend on
water & minerals
absorbed from the
soil by roots
Plant Structure
sugars
water &
minerals

Dermal
◦ epidermis (“skin” of
plant)
◦ single layer of tightly
packed cells that covers
& protects plant

Ground
◦ bulk of plant tissue
◦ photosynthetic
mesophyll, storage

Vascular
◦ transport system in
shoots & roots
◦ xylem & phloem
Plant Tissues

Parenchyma
◦
◦
◦
◦

“typical” plant cells = least specialized
Thin walls
Photosynthesis, storage, & secretion
tissue of leaves, stem, fruit, storage roots
Collenchyma
◦ Thick but flexible cell walls
◦ Support functions

Sclerenchyma
◦ Thickest walls
◦ Support functions
◦ dead at functional maturity
Plant Cell Types
 Parenchyma cells are unspecialized, thin, flexible &
carry out many metabolic functions

all other cell types in plants develop from parenchyma
Parenchyma
 Collenchyma cells have thicker primary walls &
provide support


help support without restraining growth
remain alive in maturity
Collenchyma
the strings in celery stalks
are collenchyma

Thick, rigid cell wall
◦ lignin (wood)
◦ cannot elongate
◦ dead at maturity

Cells for support
◦ xylem vessels
◦ xylem tracheids
◦ fibers
 rope fibers
◦ sclereids
 nutshells
 seed coats
 grittiness in pears
Sclerenchyma
vessel elements
 Xylem

vessel
element

Vascular tissue
move water & minerals up from roots
dead cells at functional maturity
 only cell walls remain
 need empty pipes to efficiently move H2O
 transpirational pull
dead cells
Structure–Function
again
tracheids
 carry sugars & nutrients throughout plant
sieve tube
companion cell
sieve plate
plasmodesmata
living cells
Phloem: food-conducting cells
 sieve tube elements & companion cells
Phloem: food-conducting cells

Living cells at functional maturity
◦ cell membrane, cytoplasm
Structure–Function
again
 control of diffusion
◦ lose their nucleus, ribosomes & vacuole
 more room for specialized transport of
liquid food (sucrose)
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Cells
◦ sieve tubes
 sieve plates — end walls — have pores to facilitate
flow of fluid between cells
◦ companion cells
 nucleated cells connected to the sieve-tube
 help sieve tubes
Phloem
dicot
monocot
trees & shrubs
grasses & lilies
collect annual rings
Vascular tissue in stems
phloem
xylem
Vascular tissue in roots: dicot
xylem
phloem
Vascular tissue in roots: monocot

Obtaining raw materials
◦ sunlight
 leaves = solar collectors
◦ CO2
 stomates = gas exchange
◦ H2O
 uptake from roots
◦ nutrients
 uptake from roots
Putting it all together