B. Life Systems · Biodiversity

Classifying Plants, Fungi and Microorganisms

B2.1 A1.2 A1.4About 50 minutes

Learning goals

I can describe the distinguishing characteristics of mosses, ferns, conifers and flowering plants.
I can explain why fungi are not plants.
I can describe protists and bacteria, including ways they help and harm us.
I can plan and carry out a safe fair test with mould.

Words to know

vascular plant
A plant with tubes inside it that carry water and food, such as ferns, conifers and flowering plants.

non-vascular plant
A small plant without tubes for carrying water, such as moss.

spore
A tiny cell that can grow into a new organism. Mosses, ferns and fungi make spores.

conifer
A plant that makes seeds in cones, such as pine, spruce and tamarack.

flowering plant
A plant that makes flowers, and seeds inside fruits.

mycelium
The mass of tiny threads that makes up the main body of a fungus, usually hidden in soil or wood.

decomposer
An organism that breaks down dead things and wastes, returning nutrients to the soil.

microorganism
A living thing too small to see without a microscope.

The biggest living thing you've never seen

Under a forest floor, threads of fungus can spread through the soil for a very long distance. You only notice the fungus when a mushroom pops up after a rainy day. The mushroom is just the part that makes spores, like an apple on a hidden tree.

Today you will classify organisms that people often overlook: plants that don't flower, fungi, and the tiny living things all around and inside you.

A cluster of tan mushrooms with raindrops on their caps, growing from wet leaves and moss. — These mushrooms are only the spore-making parts of a fungus. Most of the fungus is a web of threads hidden in the soil. (Never touch or eat wild mushrooms.) AI-generated image

Remember from Grade 3

In Grade 3 you learned that plants make their own food by photosynthesis, and that seeds can come from flowers, fruits and cones. Now you will use those characteristics to classify plants.

Classifying plants

All plants have many cells and make their own food by photosynthesis. Scientists sort them using two main questions: Does it have tubes (vessels) to carry water? and Does it make seeds?

Plant group	Tubes for water?	Seeds or spores?	Ontario examples
Mosses	no (non-vascular); small, grow in damp places	spores	sphagnum moss in bogs, moss on rocks and logs
Ferns and horsetails	yes (vascular)	spores (often in dots under the leaves)	bracken fern, ostrich fern (its young curled shoots are fiddleheads)
Conifers	yes	seeds in cones; most keep needles all year	eastern white pine, white spruce, eastern white cedar, tamarack
Flowering plants	yes	seeds inside fruits, made from flowers	sugar maple, white trillium, grasses, corn, apple tree

Four major groups of plants. Fun fact: the tamarack is a conifer that loses its needles every fall.

A key for the four plant groups. Two questions do most of the work: Does it have tubes for water? and Does it make seeds?

Fungi: not plants!

Mushrooms grow in the ground, so people once thought they were plants. But fungi are different:

Fungi cannot make their own food. They have no chlorophyll for photosynthesis.
They absorb food from what they grow on: dead logs, leaves, soil, bread, or sometimes living things.
Most fungi are made of mycelium: a network of tiny threads. A mushroom is only the spore-making part.
Yeast is a fungus with only one cell. Bakers use it to make bread rise.

Many fungi are decomposers. Without them, dead leaves and logs would pile up and nutrients would not return to the soil. Some fungi also partner with tree roots and help trees take in water and nutrients.

A lichen, the crusty patch you see on rocks and tree bark, is a partnership: a fungus living together with an alga (or a kind of bacteria) that makes food by photosynthesis.

Most of a fungus is hidden. The mycelium spreads through the soil or a log and absorbs food; the mushroom is just the part that makes spores.

The tiny ones: protists and bacteria

Protists are mostly single-celled, and their cells have a nucleus. A drop of pond water can hold:

Amoebas, which change shape as they move and swallow food.
Paramecia, which are covered in tiny hairs that beat to move them.
Algae, which make food by photosynthesis. Some algae are single cells; others, like seaweeds, are large.

Bacteria are single cells with no nucleus. They live almost everywhere: soil, water, air, and on and inside your body.

Helpful bacteria: they turn milk into yogurt, help digest food in your gut, decompose dead things, and some live in bumps on the roots of bean and pea plants, adding nitrogen that plants need to the soil.
Harmful bacteria: some cause illnesses, such as strep throat. Washing your hands removes many germs.

Worked example

Let's classify these organisms

Classify each one: eastern white pine, bracken fern, sphagnum moss, white trillium, a puffball (round mushroom), baker's yeast, paramecium, the bacteria in yogurt.

Eastern white pine: plant, has tubes, seeds in cones → plant, conifer.
Bracken fern: plant, has tubes, spores under its leaves → plant, fern.
Sphagnum moss: small plant, no tubes, spores → plant, moss.
White trillium: has flowers and makes seeds in a fruit → plant, flowering plant.
Puffball: cannot make food, releases spores, grows from mycelium → fungus.
Baker's yeast: one cell, absorbs sugar, used in bread → fungus (single-celled).
Paramecium: one cell with a nucleus, moves with tiny hairs → protist.
Yogurt bacteria: one cell, no nucleus → bacteria.

Ask: Does it make its own food? Does it have one cell or many? Does its cell have a nucleus? Seeds or spores? Cones or fruits?

Just for fun

Why did the mushroom get invited to every party?

Because he was a fun-gi!

Seeds vs spores

A seed contains a tiny baby plant and stored food, wrapped in a seed coat. A spore is just one cell, much smaller and lighter. Mosses, ferns and fungi spread by spores, which can drift a long way on the wind.

Hands-on activity

Fair test: what makes mould grow faster?

Question: Does bread grow mould faster when it is damp or dry?

You need: 2 slices of the same bread, a spray bottle or a few drops of water, 2 zip-top bags, tape, a marker, a magnifying glass.

Predict: write which slice you think will grow mould first and why.
Wipe each slice lightly on a kitchen counter or rub it on a dusty windowsill to pick up spores (they are everywhere in the air).
Change only one thing (the variable you test): sprinkle about 5 drops of water on one slice. Leave the other dry.
Keep everything else the same: same bread, same size, same place (a dark cupboard), same number of days.
Seal each bag, then tape it shut. Label them "damp" and "dry".
For 7 to 10 days, look through the bag each day. Record the date, colour and how much of the slice is covered (none, a little, half, most).
Conclude: did your results support your prediction? What would you change next time?

Safety (very important): never open the bags. Mould spores can make people sick or cause allergies or asthma attacks. Anyone with mould allergies or asthma should not do this activity. When finished, a grown-up throws the sealed bags in the garbage. Wash hands after handling the bags.

What to look for: a clear prediction, one changed variable, a daily record, and a conclusion. Usually the damp slice grows mould first, because fungi need moisture.

Your turn

Name the four plant groups in the table.

Which plant group has no tubes to carry water?

How do conifers carry their seeds? How do flowering plants?

Give two reasons fungi are not plants.

What is a lichen?

Name one helpful and one harmful thing bacteria do.

What is the difference between a protist and a bacterium?

More practice: warm-up

Is yeast a plant, a fungus or a bacterium?

Which makes spores: a fern or a maple tree?

Is a white spruce a conifer or a flowering plant?

What do decomposers do?

Why must you never open the mould bags?

More practice: on your own

Ferns and mosses both make spores. How are they different?

In the mould test, what is the one variable you change, and name two variables you keep the same.

Why would a forest have problems without fungi?

A student says, "All bacteria are germs that make us sick." Correct this statement.

A plant has needles and cones but loses its needles in fall. Which group is it in, and what might it be?

Challenge

Your damp slice and dry slice were both left in a sunny window instead of a cupboard. Would the test still be fair? Explain.

Algae make their own food like plants, but in the six-kingdom system most algae are classified as protists, not plants. Suggest a reason.

Bean plants have bacteria living in bumps on their roots. Explain how both partners might benefit.

Check your understanding

Quiz

Which plant group makes seeds inside cones?

Fungi are not plants mainly because they...

Which organism is a single cell with no nucleus?

Mosses and ferns both spread by...

In a fair test, you should...

A lichen is made of...

For parents and teachers

Big idea: plants are classified by whether they have water-carrying tubes and whether they make seeds (in cones or fruits) or spores. Fungi are not plants: they absorb their food. Protists and bacteria are mostly single-celled; bacteria have no nucleus.

How to help at home:

Look at the underside of fern leaves for spore dots, compare a pine cone with an apple's seeds, and notice moss in damp, shady spots.
Help with the mould fair test and talk about the one variable being changed.

Safety for the mould test: keep the bags sealed and taped, never open or sniff them, skip the activity if anyone at home has mould allergies or asthma, and throw away the sealed bags at the end. Never let your child taste wild mushrooms; many are poisonous.

Common difficulties:

Calling mushrooms plants.
Thinking all bacteria are harmful.
Changing more than one thing in a fair test.