Download What does a stem do? Parts of the stem

Botany for Master
Gardeners Part II
What you should know by the end
of today’s session
Selected plant parts and their
How to tell a stem from a root
“reasons for being”
How to recognize a simple and
compound leaf
How to describe how water gets to the
top of trees
How to tell a monocot from a dicot
What does a stem
do?
Physically support leaves,
flowers & fruits
Transport water, minerals
& nutrients
Parts of the stem
node = place
where leaf is
(or was)
attached to
the stem
internode =
distance
between nodes
Provides storage in some
plants
Note: Stem parts are important in plant identification!
terminal bud
One year
of growth
from one
bud scar to
another
A closer look at buds
bud scales
axillary or
lateral bud
leaf scar
bud scale scar
node
http://www2.una.edu/pdavis/images/trees/twigs/fraspcm.jpg
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lateral bud
Let’s
review
bud scale scars
leaf scar
Lateral or axillary buds
Located in the angle
where the leaf
attaches to the stem
Axillary bud
may produce lateral
shoot or branch
Terminal bud
What’s inside the
stem?
apical
meristem
vascular
bundles
leaf
primordia
axillary buds
internode
node
corn
cortex cells add
structural
strength to the
stem
2
phloem
phloem
on the outside
vascular
bundle
xylem
on the inside
Notice the positions
of the tissues as
related to the outer
layer of the stem!
Stem cross-section
Herbaceous monocot
(corn)
What does the phloem
do?
transports nutrients in
sap
What does the xylem
do?
xylem
transports water and
minerals
Cross-section of stems
Herbaceous monocot
(corn)
Herbaceous dicot
(clover)
Herbaceous dicot
(clover)
phloem
Note: A vascular cambium
is between the xylem and
phloem in dicots, but not in
monocots
xylem
Notice the relative position
of the xylem and phloem!
Stem cross-sections
Herbaceous
monocot (corn)
What else to you notice?
A dicot stem has vascular bundles in a ring
vascular
cambium
Woody dicot
(maple tree)
3
vascular
cambium
vascular
cambium
bark
phloem
xylem
bark
phloem
xylem
What’s this
area?
www.unlv.edu/.../ Secondary/Secondary.html
Vascular cambium
o Cambium is a meristematic tissue, meaning it
divides to produce new tissues
o Cambium divides to produce
o xylem: to the inside (heartwood, pith)
o phloem: to the outside (part of bark)
o Responsible for “girth growth,” or increased
stem diameter in woody plants
Xylem cells
o Carry H2O & dissolved
nutrients
o Cells are:
o long, open-ended,
connected end to end
o have thick cell walls
o resemble straws
?
What is bark?
Answer. Bark is the outer layer
of cells on a tree containing
cambium, compressed phloem,
and cork
?
What direction
does the xylem
transport its
materials?
Answer: xylem cells
transport water and
minerals primarily from
the soil upwards
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?
Phloem cells
What direction
does the phloem
transport its
materials?
o Transport actively
photosynthetic products
o from leaves to roots,
stems, flowers &
fruits
o Cells are:
o long and tube-like
o without extra cell
wall thickening
Answer: Phloem cells
transports nutrients
downward, sideways, and
even “up” wherever the
plants needs the energy
Let’s review vascular
bundles
Phloem transports
photosynthetic products to
areas of the plants
needing energy
Vascular bundle
Xylem is like tiny straws
and transports water and
minerals from the soil to
other parts of the plant
What do roots do?
o take up water and
minerals
o anchor the plant
o store food reserves in
over-wintering perennials
Kinds of root systems
o tap root, can be
large of narrow
o fibrous or lateral
roots form a
network in the
ground
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What’s inside a root?
?
How does this
differ from a
stem?
Answer: The
vascular system is
in the center
buttercup
What’s inside a root?
cortex
xylem
phloem
cambium
in woody
roots
buttercup
Unique to roots!
Origin of lateral roots
root cap located at root
tip & protects
growing point
root cap
Notice the root cap on the lateral root
Root hairs, another
unique feature
?
What is the
function of root
hairs?
Answer: Absorb water and
minerals from the soil
Root hairs on a radish
seedling
Root hairs
• delicate
• thin-walled
• room for lots of
water
• has lower
water pressure
than the
outside soil
http://iweb.tntech.edu/m
caprio/Root_hair_BW.J
PG
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What do
leaves do?
Major leaf parts
• lamina (leaf blade) highly variable in size
and shape
o photosynthesize
o respire
o transpire
• petiole - stalk at base
of leaf that attaches
leaf blade to stem
Leaf vein patterns
Remember monocots & dicots?
leaf blade
petiole
http://www.csdl.tamu.edu/FLORA/201Manhart/veg/leaf.venation/image1.gif
dicots
monocot
Let’s
practice
Monocot or
Dicot?
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Compound vs. Simple
leaves
?
?
Simple leaf
Buds are in
the axils
between leaf
and stem
Hint: Where is lateral bud?
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Compound leaves
Simple or compound?
leaflet
pinnately compound
palmately compound
Where is the bud?
leaflet
pinnately compound
?
simple
?
?
pinnately compound
?
leaflet
palmately compound
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Albizzia –
bipinnately
compound
What is
photosynthesis?
Answer. Photosynthesis is the
process whereby plant use the
energy of light to convert carbon
dioxide and water to sugars
http://www.eeb.uconn.edu/Courses/EEB271/Fabales/Albizzia%20leaves.jpg
?
Sugars produced through
photosynthesis are the building
blocks of life as we know it
What is respiration?
In
Out
carbon
dioxide,
sugars
water
water
oxygen
Answer. Respiration is the opposite
of photosynthesis
In respiration, sugars, water, and
oxygen are used and carbon dioxide
and water are released
The photosynthesis factory
Epidermis
True or False ?
Only plants photosynthesize
and only animals respire
Answer: Only plants
What is the leaf epidermis?
Answer: The epidermis is the top
and bottom layer of cells on a leaf
photosynthesize but both
plants & animals respire
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Leaf model
What do stomates
do?
mesophyll
open
closed
Stomates are small pores on the leaf
epidermis used for gas exchange
What is transpiration?
Answer: Transpiration is water loss
(as vapor) from a plant
Transpiration rate is controlled by
opening and closing of the stomates,
which is influenced by humidity,
temperature, and light
The Elements . . .
Finally!
Putting it all together
?
How does water get from
the soil to the top of a
tree?
Let’s review
Root hairs (often with the help of
mycorhizzae) absorb water from the soil
Name three critical processes carried
out by leaves
Xylem cells transport water via capillary
action and cohesive force of water
Answer: photosynthesis, respiration, and
transpiration
Stomates control evaporation which
creates a lower pressure in the
vascular system
What role does transpiration play in
water movement in plants?
Answer: transpiration creates a lower
pressure in the vascular system which
draws water from the soil
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What do flowers do?
o reproduce – It’s all
about sex
o if fertilization occurs,
seeds are produced
and carried in cones
(conifers) or fruits
(flowering plants)
flower
It is not always
what it seems!
Parts of a flower
filament
anther
style
stigma
Lily
Flower parts
anther
stigma
sepal
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Flower Types
• Complete – Has all floral parts
present (sepals, petals, stamens,
pistils)
• Incomplete -flower lacks 1 or more
of the 4 parts
Complete or Incomplete?
begonia
“male” flower
“female” flower
(staminate)
(pistillate)
Kinds of plants with catkins are usually
imperfect. Can you think of more examples?
poplar
Flower Types, Continued
• Perfect – Has both stamens and
pistils (male and female parts)
• Imperfect – Lacks either stamens
or pistils
New Question.
Perfect or Imperfect?
begonia
Answer: These are imperfect flowers.
Perfect flowers have both male and
female parts in the same flower
Remember, It’s
All About Sex!
alder
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pollen on sticky
surface of stigma
pollen grains
Fertilization
pollen tube
ovule
ovary
Ovary
cross-section of ovary
Guess the pollinator
The old birds and bees thing
big leaf maple
willow
beetles
wind
cape fuchsia
hummingbirds
Guess the pollinator
yarrow
skunk cabbage
butterflies
flies
cat’s ear
bees
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One More Thing to Learn
Question: What is the floral
difference between monocots and
dicots?
Answer: Monocots have flower parts
in multiples of 3; Dicots are in
multiples of 2, 4 or 5
Summary of differences,
monocots & dicots
Time to practice
with pictures!
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Fun Activity
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Resources
Capon B, 1990.
Botany for
gardeners,
Timber Press,
Portland OR, 220
pp. ISBN 088192-258-7
(paper).
Resources
Baumgardt, John Philip.
1992. How to identify
flowering plant families:
a practical guide for
horticulturists and plant
lovers. Timber Press,
Portland, OR, 269 pp.
ISBN 0-917304-21-7.
Resources
Elpel, Thomas.
1967. Thomas J
Elpel’s herbal field
guide to plant
families, 4th ed.,
HOPS Press,
Pony, MT, 196 pp.
ISBN 1-89278407-6.
Acknowledgements
Web Sources
U WI – Stevens Pt
U CT
UC Davis
U Florida
U Chicago
U Texas
WSU
CO St U
Purdue U
UC Berkeley
Ohio St U
OSU
CA St U Stanislaus
U NE Lincoln
UCLA
Botanical Soc America
U NM
Rutgers U
Southern IL U
U System GA
Princeton U
U KY
U North AL
Texas A&M U
U WI – Madison
Sidwell Friends School
U HI
IA St U
Stanford U
Queens U Charlotte
Eastern OR U – La Grande
Texas Tech U
U IL Urbana-Charlotte
U of MD
U AZ
Vanderbilt U
U Miami
MI St U
Many photographs by Linda
R McMahan, OSU Extension,
Yamhill County
Cleveland St U
Grand Rapids Comm C
Wilkes U
Cornell U
Stony Brook U
Maricopa Comm C
Some slides from an original
presentation prepared by Ann
Marie VanderZanden
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