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Selected plant parts and their

“reasons for being”

Botany for Master Gardeners Part II

What you should know by the end of today’s session

How to tell a stem from a root

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

Provides storage in some plants

Parts of the stem

Note: Stem parts are important in plant identification!

node = place where leaf is

(or was) attached to

the stem

internode = distance

between nodes

terminal bud

axillary or lateral bud

leaf scar

bud scale scar

node

bud scalesOne year of growth from one bud scar to another

http://www2.una.edu/pdavis/images/trees/twigs/fraspcm.jpg

A closer look at buds

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lateral bud

leaf scar bud scale scars

Let’s review

Lateral or axillary buds

Located in the angle where the leaf attaches to the stem

Axillary budmay produce lateral shoot or branch

apical meristem

internode

node

axillary buds

Terminal bud

leaf primordia

What’s inside the stem?

cortex cells add structural strength to the stem

vascular bundles

corn

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vascular bundle

xylem

phloemon the outside

on the inside

Notice the positions of the tissues as related to the outer layer of the stem!

xylem

phloem What does the phloem do?transports nutrients in sap

What does the xylem do?

transports water and minerals

Stem cross-section

Herbaceous dicot(clover)

Herbaceous monocot(corn)

xylem

phloem

Notice the relative position of the xylem and phloem!

Cross-section of stemsHerbaceous dicot

(clover)Herbaceous monocot

(corn)

What else to you notice?

Note: A vascular cambium is between the xylem and phloem in dicots, but not in monocots

A dicot stem has vascular bundles in a ring

Herbaceousmonocot (corn)

Stem cross-sectionsWoody dicot(maple tree)

vascular cambium

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vascular cambium

bark

phloem

xylem

What’s this area?

www.unlv.edu/.../ Secondary/Secondary.html

vascular cambium

phloem xylem

bark

Vascular cambiumo Cambium is a meristematic tissue, meaning it

divides to produce new tissueso 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

?What is bark?

Answer. Bark is the outer layer of cells on a tree containing

cambium, compressed phloem, and cork

o Carry H2O & dissolved nutrients

o Cells are:o long, open-ended,

connected end to end o have thick cell wallso resemble straws

Xylem cells ?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 cellso Transport actively

photosynthetic productso from leaves to roots,

stems, flowers & fruits

o Cells are:o long and tube-likeo without extra cell

wall thickening

?What direction

does the phloem transport its materials?

Answer: Phloem cells transports nutrients downward, sideways, and even “up” wherever the plants needs the energy

Let’s review vascular bundles

Vascular bundle

Phloem transports photosynthetic products to areas of the plants needing energy

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 planto 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?

buttercup

Answer: The vascular system is in the center

What’s inside a root?

buttercup

xylemcortex

phloemcambium in woody roots

Unique to roots!root cap -located at root tip & protects growing point

root cap

Origin of lateral roots

Notice the root cap on the lateral root

Root hairs on a radish seedling

Root hairs, another unique feature

?What is the function of root hairs?

Answer: Absorb water and minerals from the soil

Root hairs• delicate

• thin-walled

• room for lots of water

• has lower water pressure than the outside soil

http://iweb.tntech.edu/mcaprio/Root_hair_BW.JPG

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What do leaves do?

o photosynthesizeo respireo transpire

Major leaf parts

• lamina (leaf blade) -highly variable in size and shape

• petiole - stalk at base of leaf that attaches leaf blade to stem

http://www.csdl.tamu.edu/FLORA/201Manhart/veg/leaf.venation/image1.gif

Leaf vein patterns

leaf blade

petiole

Remember monocots & dicots?

dicots monocot

Let’s practice

Monocot or Dicot?

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Compound vs. Simple leaves

Hint: Where is lateral bud?

Simple leaf

Buds are in the axils between leaf and stem

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Compound leaves

pinnately compoundpalmately compound

leaflet

Simple or compound?

Where is the bud?

pinnately compound

leaflet

? simple ?

palmately compound

leaflet

? ?pinnately compound

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?

Albizzia –bipinnately compound

http://www.eeb.uconn.edu/Courses/EEB271/Fabales/Albizzia%20leaves.jpg

What is photosynthesis?

Answer. Photosynthesis is the process whereby plant use the energy of light to convert carbon dioxide and water to sugars

Sugars produced through photosynthesis are the building blocks of life as we know it

carbon dioxide,

water

sugars

oxygen

water

In Out

The photosynthesis factory

What is respiration?Answer. Respiration is the opposite of photosynthesis

In respiration, sugars, water, and oxygen are used and carbon dioxide and water are released

True or False ?Only plants photosynthesize and only animals respire

Answer: Only plants photosynthesize but both plants & animals respire

Epidermis

What is the leaf epidermis?

Answer: The epidermis is the top and bottom layer of cells on a leaf

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Leaf model

mesophyll

open closed

What do stomates do?

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

Finally!Putting it all together

?How does water get from

the soil to the top of a tree?

The Elements . . .

Stomates control evaporation which creates a lower pressure in the vascular system

Root hairs (often with the help of mycorhizzae) absorb water from the soil

Xylem cells transport water via capillary action and cohesive force of water

Let’s review

Name three critical processes carried out by leaves

Answer: photosynthesis, respiration, and transpiration

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

stigma

anther

filament

style

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

Flower Types, Continued

• Perfect – Has both stamens and pistils (male and female parts)

• Imperfect – Lacks either stamens or pistils

Complete or Incomplete?

“male” flower

(staminate)

“female” flower

(pistillate)

begonia

New Question.

Perfect or Imperfect?

begonia

Answer: These are imperfect flowers. Perfect flowers have both male and female parts in the same flower

poplar alder

Kinds of plants with catkins are usually imperfect. Can you think of more examples? Remember, It’s

All About Sex!

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Ovary

cross-section of ovary

pollen on sticky surface of stigma

Fertilization pollen grains

ovary

pollen tube

ovule

The old birds and bees thing

beetles wind hummingbirds

Guess the pollinator

big leaf maple cape fuchsiawillow

butterflies flies bees

Guess the pollinator

yarrow skunk cabbage cat’s ear

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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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Capon B, 1990. Botany for gardeners, Timber Press, Portland OR, 220 pp. ISBN 0-88192-258-7 (paper).

Resources

Elpel, Thomas. 1967. Thomas J Elpel’s herbal field guide to plant families, 4th ed., HOPS Press, Pony, MT, 196 pp. ISBN 1-892784-07-6.

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.

ResourcesAcknowledgements

Web Sources

UC Davis

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U HI

Queens U Charlotte

U IL Urbana-Charlotte

U AZ

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U WI – Stevens Pt

U Florida

WSU

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Botanical Soc America

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Eastern OR U – La Grande

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Maricopa Comm C

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U NE Lincoln

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Sidwell Friends School

Stanford U

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Many photographs by Linda R McMahan, OSU Extension, Yamhill County

Some slides from an original presentation prepared by Ann Marie VanderZanden