Download Science of Life Explorations: What Makes a Plant a Plant?

Science of Life Explorations
Plant Anatomy:
What Makes a Plant a Plant?
What do you know about plants? We’re going to take a closer look at the
anatomy of plants we have in our gardens and fields. ANATOMY is a science of
the structure of an animal or plant or one of its parts.
The plants we have in our neighborhoods generally have three major traits
in common. They have roots, stems and leaves. There are other types of
plants like primitive mosses and ferns whose plant parts are not so easy to
recognize. Did you know that cacti do not have leaves!
Their thick, padded stems do the work of leaves!
What makes a plant a plant?
What are three important plant parts?
How do plant roots work?
What is a stem?
Why do plants have leaves?
What makes a plant a plant? The ability to make their own food energy!
Plants have a lot of variety and can appear to be very different because they
are adapted to many different environments. One of these below is a tropical
plant and prefers heat, humidity and wet soil. One is found in very hot, dry
environments and doesn’t have leaves. Choose one of the plants below and
describe how it appears to be the same or different than the others.
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In general, most plants have roots, leaves and stems. Have you ever looked
at plants and noticed the TRAITS that they share? The next time you are
outside, compare plants you find in vegetable gardens, flower gardens, parks or
fields. Look at small plants, shrubs and trees.
Let’s think about plants that you could find in your yard or garden or
neighborhood. What are three important plant parts to consider?
1._______________________________
2._______________________________
3._______________________________
Of these three, do you think one is more
important than the others, or do you think they
are equally important?
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In our soil lessons, we talked about how water, nutrients and air in the soil are
needed by plants. Roots have many ESSENTIAL roles. They support the plant,
keeping it in the soil. They take in water and nutrients from soil. Much of the
food energy created by leaves is stored in the plant’s roots. Even when plants
appear to be dead or DORMANT in the winter, plant roots are hard at work!
When plant roots are injured or exposed to diseases or other pests, the plant suffers.
What is a stem? The very first thing that grows
out of a seed is the root. It grows down through
soil. Next comes a shoot. That shoot becomes
the main stem of the plant.
In the case of some plants, like corn, that stem
will get bigger around and taller but will never
make new stems or branches. In the case of
other plants, that stem will become sturdier and
produce branches.
The main stem of some plants may grow large but
stay green. The main stem of other plants grows
tough and woody and then we call it a TRUNK!
When planting, be careful that you
do not injure the stem or trunk of
the plant. For Example, although
tree trunks seem tough, they can
be damaged.
Give the roots plenty of space to
spread out in soft soil for best
results.
1. outer bark
2. PHLOEM - a layer of cells
that carry food energy from
the leaves to the roots
3. CAMBIUM - a layer of cells
that produces new growth of
phloem and xylem cells each
year, causing the tree to
grow larger.
4. XYLEM - a layer of cells
that carries water and
nutrients from the roots to
Reproduced by permission of Morton Publishing from the leaves.
Van De Graaff and Crawley, A Photographic Atlas for
the Biology Laboratory, 5th Edition. © 2005
Why do plants have leaves? Leaves do the major work of PHOTOSYNTHESIS.
Leaves gather sun energy and CARBON DIOXIDE. They also release water
vapor and OXYGEN. Inside the leaf, plant cells are using carbon dioxide, sun
energy, water and nutrients to create food energy for the plant.
Plant leaves VARY greatly. They all have the purpose of collecting sun energy,
carbon dioxide and water. Look closely and you’ll see that leaves can be
light green, dark green, yellow, thin, thick, fuzzy, smooth, sharp-edged,
smooth-edged, round, pointed, large or small. They can come in groups of one,
two, three, or many more. Some leaves are so different, we call them needles.
This is a great time to take a walk outside and examine the leaves of many
types of plants. You may even have house plants. Don’t forget the leaves of
vegetables and fruits! Compare the leaves below. Do you recognize any of
these plants?
Leaves are famous for one other thing, aren’t they? They fall! Actually,
not all leaves fall, but many do. Most fallen leaves come from plants called
BROADLEAF plants. The National Arbor Society likes to consider trees to
be in two categories: BROADLEAF or CONIFER. Conifers generally have
NEEDLES. Circle the plant above that has needles instead of a ‘broadleaf’.
Plant Anatomy Review:
Plants are unique because they have the ability to make their own food energy!
Most plants have roots, stems and leaves. These plant parts do the same types of
work, but they may vary quite a lot.
Plant roots work all year long to collect water and nutrients. They store energy.
We don’t usually see plant roots, but when they are injured or exposed to
diseases, the plant will have problems, too.
Plant leaves can be many shapes, sizes and thicknesses. When people talk about
shrubs and trees, they may separate them into groups called broadleaf plants and
conifer plants. Conifers usually have needles. Needles are special leaves that
usually stay on the plant all year long. Because of this, many people call them
evergreens.
Test Yourself!
1. When comparing plants look at their three main traits. List them here:
______________, __________________, ________________
2. Plants are unique because they are able to make their own
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3. What is one job of the roots seen in this illustration?
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Vocabulary
anatomy - the science that deals with the structure of an animal or plant or one
of its parts
angiosperm - the scientific name for plants that produce flowers as part of
their life cycle
annual - plants that survive one growing season in a particular area
broadleaf - the term for plants that have broad leaves rather than needles
cambium- a layer of cells under bark and phloem; new cells are formed along
this layer which cause the plant to grow larger each year
carbon dioxide - a gas in our atmosphere that plants use to make their own food
energy; animals exhale carbon dioxide into the air
chloroplasts - an important part of plant cells that enables plants to create
food energy for themselves in the process of photosynthesis
circumference - the measurement of something all the way around it
conifer - a term for plants that produce narrow needle-like leaves rather than
broad leaves
consumers - animals or people that acquire (eat, buy, take) products created by
others
cotyledon - the first and very important leaf or leaves of flowering plants
crown - a tree crown is all the branches and leaves of the tree; a plant crown
is the base of the plant at ground level, above the roots and the source of new
leaf growth
deciduous - the term for woody plants that drop their leaves before winter
dicot - the term for a flowering plant which produces two leaves on its shoot
and will develop branches and leaves when mature
dormant - for plants, this means active growth stops due to a change in season
essential -something that is very important and needed
estimate - a good guess or calculation of something based on the information
you can gather about it
evapo-transpiration - the way that plants release water back into the soil
through their leaves; it is a form of evaporation when water changes into a
vapor
evergreen -the general term used for plants that don’t lose their leaves; most
are conifers, but not all
gymnosperm - the scientific name of plants that don’t produce flowers but
create seed-bearing cones instead
herbaceous - plants that do not produce a woody covering to their stems and
generally die back in the winter
monocot - plants that send up one shoot and one new leaf only, and will mature
to have only one stem
needles - the name for the narrow ‘needle-like’ leaves of conifers
oxygen - the gas found in our atmosphere that animals must inhale to to nourish
their cells and stay alive; plants release oxygen
perennial - plants that complete a life cycle in one season and resume growth
again for more than one year
phloem - phloem is the part of plants that transports food energy from leaves
down to the roots.
photosynthesis - the way plants create their own food energy
protista - the scientific kingdom that includes fungi, molds, algae and other
organisms
shrub - similar to a tree but usually has more than one woody stem
stem - the stalk or trunk of a plant; there can be one or many stems on a plant
trait - a quality of or a feature of something that stays constant
trunk - the woody stem of some plants, especially shrubs and trees
turf - grass that is grown and maintained to be a lawn or outdoor use area
unique - one of a kind; not like others
vary - to show variety or differences
vascular bundles - plant tissue that acts as waterways to move food energy,
nutrients and water throughout the plant
veins - tube-like structures which allow water and sugars to travel through
plants or in the case of animals, blood to the heart
woody - a plant that has bark over its stem rather than soft green tissue
xylem - xylem is the part of a plant that transports water and nutrients up to
leaves
For Teachers and Parents
During many previous lessons we have often touched on the ways plants are an intricate
part of our lives. We hope that somewhere near your school, you have an area to take
your students for a walk sometime during this lesson. Even the smallest houseplant
would be a good place to start.
Plants are about as diverse as they can be and are so much a part of our lives that we
tend to take them for granted. After all, the photosynthetic quality of plants enables
us to have a renewable source of oxygen. Plants offer shade, food, oxygen and more.
Reconnecting with the natural world happens quickly for students when they can examine
plants directly.
This lesson starts with some plant basics: Almost all plants have roots, stems and
leaves. This may surprise you. Don’t all plants have leaves? No. Cacti use their
thickened stems to do the work of leaves! These three major plant parts are the focus
of any study of plants. But what makes plants so unique? They are capable of creating
their own food energy. The rest of us are consumers. Even mushrooms, once considered
plants, can not use photosynthesis. Plants are the basis for almost any food chain.
As students learn about the roots, stems and leaves of plants, they will also be exposed
to the many ways plants are different from one another. Plants are broken down into
smaller groups by comparing the way they grow and reproduce. This lesson offers some
of those comparison:
Some plants have flowers and fruit in their life cycles (angiosperms) while others use rudimentary flowers and cones (gymnosperms)
Some plants start out with one leaf (monocot) and others with two (dicot) and mature to be very different types of plants
Some plants have broad leaves (broadleaf) and some have needle leaves (conifer)
Some plants drop their leaves (deciduous) and some don’t (evergreen or conifer)
Some plants have stems that stay green (herbaceous) and some develop bark (woody)
Students will have opportunities to measure the size of trees, compare leaves and
consider how plants and people interact with the air around us (the carbon dioxide and
oxygen cycles). It will surprise many students to consider the vast ways we eat plants
other than having vegetables on our plates!
The plant anatomy lesson will touch on many subjects discussed in prior lessons and
reinforce them. Like animals, plants have a way of helping humans remember they are
part of a large interactive environment. We hope the plant anatomy unit increases
interest in plants for your students.
A major part of IPM, integrated pest management is to learn about the life cycles and
biology of what we are dealing with. Basic plant knowledge is a good start.
Pg 1 This lesson contains many references to the ways plants are the same, and
different.
The essential questions listed are a good start for class discussion. Throughout these
lesson activities, any opportunity to examine live plants is beneficial.
Pg 2 The four plants illustrated here are a water-loving tropical plant, a cactus plant,
a sunflower, and the branch of a shrub showing fruits. Students are asked to compare
one of these plants with the others. They may consider the locations where the plant
grows. Presence of fruit or seeds or flowers, shapes, textures, colors and use. Because
these plants are representative only, this writing exercise is not meant to examine facts
but to encourage thought.
Pg 3 All plants reproduce by some means, but remind students that not all plants have
flowers. We will discuss plant life cycles in the next lesson. One focus of this lesson is to
reinforce to students that plants use roots, stems and leaves to do their most important
job - photosynthesis. Throughout the previous lessons, we’ve discussed the importance
of water, soil, and sun energy to plants, and how plants interact in our world as food,
shelter and beauty to animals and humans. Have students think back and explain, in
writing, one way plants use roots, stems or leaves to function and survive.
Pg 4 When plants are young, they can lose some of their roots, and some of their
leaves, but not too many can survive the loss of their stem. We will discuss later how
some plants have one stem, such as a tree, and some have multiple stems, such as
a shrub. Perennial plants that have well-established roots can grow new stems. The
illustration of the layers of tissue under tree bark introduces some large words, but we
don’t expect students to learn these words. The concept here is plants have stems with
active layers or waterways that move water and nutrients and sugars (self-made food
energy).
Most students will know that in woody stems, each years’ growth adds a ring of tissue.
Pg 5 This is a great time to explore the outdoors and collect leaves. Another option
is to have students design a leaf of their own and describe the plant it came from.
Remind students that leaves tend to be symmetrical.
Test Yourself!
1. When comparing plants look at their three main traits. List them here:
roots
stems
leaves
______________, __________________, ________________
2. Plants are unique because they are able to make their own
food, energy or food energy
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3. What is one job of the roots seen in this illustration?
gather nutrients, gather water,
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store energy, keep plant firmly in
soil, etc
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