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Selected plant parts and what they “do”

Vickie Liskey

Botany for Master Botany for Master Botany for Master Botany for Master Gardeners Part IIGardeners Part IIGardeners Part IIGardeners 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 form 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 bud

may produce lateral shoot or branch

apical meristem

internode

node

axillary buds

Terminal bud

leaf primordia

Angiosperms divided into

• Dicotyledon

Monocotyledon

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Monocots

• Fibrous root system• Vascular system in

bundles• No secondary growth• Meristems not in

terminal buds• Parallel venation

• Flower parts in 3’s• Vascular bundles are

scattered in the stems• One Cotyledon

How does grass grow?

Dicots

• Fibrous or tap root system• Vascular system forms ring in the stem

• Secondary growth common• Net venation

• Two cotyledons• Flower parts in 4’s or 5’s

•

Dicot training

• Knowing a plant is a dicot is important when you prune or pinch to shape growth.

• Removing terminal buds causes the removal of the hormone auxin that keeps the lateral buds dormant or slow growing.

• This allows you to shape the plant.

Why is a Christmas tree a triangle and not a rectangle?

Monocot Versus Dicot Plants

• Important monocots are rice, wheat and corn; oak trees and dandelions are dicots.

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What’s inside the stem?

cortex cells add structural strength to the stem

vascular bundles

corn

vascular bundle

xylem

phloem

on the outside

on the inside

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

xylem

phloemWhat does the phloem do?

transports nutrients in sap

What does the xylem do?

transports water and minerals

o Carry H2O & dissolved nutrients

o Cells are:

o long, open-ended, connected end to end

o have thick cell walls

o resemble straws

Xylem cells

Phloem cells

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

Herbaceousmonocot (corn)

Stem cross-sections

Woody dicot(maple tree)

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vascular cambium

vascular cambium

bark

phloem

xylem

What’s this area?

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

vascular cambium

phloemxylem

barkVascular 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

?What is bark?

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

cambium, compressed phloem, and cork

What do roots do?

o take up water and minerals

o anchor the plant

o store food reserves in over-wintering perennials

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Kinds of root systems

o tap root, can be large of narrow

o fibrous or lateral roots form a network in the ground

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

phloem

cambium in woody roots

Unique to roots!

root cap -located at root tip & protects growing point

root cap

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

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What do leaves do?

o photosynthesize

o respire

o 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

Compound vs. Simple leaves

Hint: Where is lateral bud?

Simple leaf

Buds are in the axils between leaf and stem

Compound leaves

pinnately compoundpalmately compound

leaflet

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Simple or compound?

Where is the bud?pinnately compound

leaflet

?

simple ? palmately compound

leaflet

?

?pinnately compound ?

Albizzia –bipinnately compound

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

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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

InOut

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

Leaf model

mesophyll

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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

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)

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flower

It is not always what it seems!

Parts of a flower

stigma

anther

filament

style

Lily

Flower parts

anther

stigma

sepal

poplar alder

Kinds of plants with catkins are usually imperfect. Can you think of more examples?

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Remember, It’s All About Sex!

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

ResourcesResourcesResourcesResources

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.

ResourcesResourcesResourcesResources

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.

ResourcesResourcesResourcesResources

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Acknowledgements Web Sources

UC Davis

U Texas

Purdue U

OSU

UCLA

Rutgers U

Princeton U

Texas A&M U

U HI

Queens U Charlotte

U IL Urbana-Charlotte

U AZ

U Miami

Cleveland St U

Wilkes U

Stony Brook U

U WI – Stevens Pt

U Florida

WSU

UC Berkeley

CA St U Stanislaus

Botanical Soc America

Southern IL U

U KY

U WI – Madison

IA St U

Eastern OR U – La Grande

U of MD

Vanderbilt U

MI St U

Grand Rapids Comm C

Cornell U

Maricopa Comm C

U CT

U Chicago

CO St U

Ohio St U

U NE Lincoln

U NM

U System GA

U North AL

Sidwell Friends School

Stanford U

Texas Tech U

Many photographs by Linda R McMahan, OSU Extension,

Yamhill County

Some slides from an original presentation prepared by Ann Marie VanderZanden