Types of Plants (With Pictures)
Most people will recognize most of the plants on this page. At the same time, we don't always pay too much attention to what makes some living things similar and what makes them different. It is not easy to see that an oak tree and a geranium are near relatives until you start to look closely.
The way we look at plants now has a lot to do with the work of Carl Linnaeus. He was a 17th Century Swedish scientist, and he wanted to work out just how many different kinds of living things there were.
He separated living things into plants and animals—in the same way that people had done for a very long time—but then went much further. He proposed groups and families where living organisms could be placed with their closest relatives. This was the beginning of modern scientific classification.
Classification has changed as science has advanced, but the Linnaean system is still in pretty good shape. On this page you will find the main groups of plants according to that system.
The Main Kinds of Plants
Plants Without Seeds
- Algae: green, brown and red (see discussion below: "Are algae really plants?")
- Ferns and horsetails
Plants With Seeds
- Cycads: palm-like plants with cones
- Ginkgo: a living fossil
- Conifers: spruce, fir, larch and so on
- Flowering plants: from oak trees to geraniums
This list covers most of the plants on our planet, but if you want a really exact understanding you will need to dig into the science. This bibliography is one place to start.
Plants Without Seeds
This is a very varied group of living things with many thousands of individual species. Most green algae live in water. Others live where it is very damp all the time; they hate being dried out.
If you see a pond where the water is green, it will probably be because millions of tiny green algae have grown there. Each alga is invisible to the naked eye.
On a seashore, you might come across kinds of green algae that are very big indeed: the green seaweeds.
Brown algae are more common in the ocean than in fresh water.
Some of the tallest plants in the world are brown algae. Giant kelp, for example, is common in shallow oceans, especially off the coast of California. It can be as tall as 250 feet!
Are Algae Really Plants?
To a scientist, the answer is "no." To most people, the answer is "yes."
Close study suggests that algae have more in common with bacteria than plants, and scientists have removed them from the plant kingdom.
Algae photosynthesise (make food from water and carbon dioxide), as do all plants, but they lack the distinctive structures of true plants like roots and leaves.
Liverworts are small plants that you see in damp places. They can stand being dried out a little better than algae, but not much.
A common kind of liverwort is pictured above. You usually see this kind near waterfalls or in woods with a lot of rain. The picture has a high magnification. These plants are pretty small!
Liverworts are believed to have evolved soon after plants made the transition from water to the land. In this sense they are more advanced than algae.
They do not have the sophisticated vessels that transport water from roots to leaves found in more advanced plants.
Mosses are close relatives of liverworts. They also like damp places and they need a lot of water to make offspring. Often mosses and liverworts fight for space around rivers and streams. Mosses don't need soil to grow, so rocks and trees can be covered in moss.
Mosses are the first plant group which show 'apical' growth. This means individual stems grow from the tip or special points along the stem, just as flowering plants do. Liverworts simply expand, growing outwards from every point.
Sphagnum moss is an especially successful moss that will grow on water. It can form floating mats many feet deep. In places, it is possible to walk on these floating mats, sometimes called "quaking bogs."
One of the strangest experiences I ever had was walking across one of these bogs. Small trees grew in the sphagnum and trees leaned to the side as I passed—my weight on the moss was enough to cause this! This is why they are called "quaking bogs."
A Quaking Bog
Ferns are far better at coping with dry periods than either algae or mosses, but still need very wet conditions to reproduce. This limits where they can grow. You will not find a fern in a desert!
Bracken is an especially successful kind of fern in countries with a cool, wet climate. It spreads quickly by using underground "creeping rhizomes" and can cover many acres very quickly.
In Devonian times, many millions of years ago, ferns were the dominant land plant on our planet. Instead of forests of fir trees or oaks, there were forests of huge tree ferns. Later on, many familiar dinosaurs like the Triceratops would be happy to dine on ferns.
Plants With Seeds
Seeds have an outer layer that helps protect against drying out, infection, or consumption by animals.
Cycads mostly grow in Central America, Africa, Southeast Asia and parts of Australia.
They are the kinds of exotic-looking plants you see in jungle movies, though some are popular house and garden plants. They like moisture and heat.
They can be tall and often have woody trunks. The leaves tend to be long and thin.
If you have grown up in a northern climate, cycads can be strange plants to encounter. Quite suddenly unfamiliar and fascinating structures will grow out of a cycad in my garden, for example, and have me hunting through my books to find out exactly what is happening.
These structures are usually cones of some kind, similar to the cones that conifers produce.
Cones bear exposed seeds rather than the kinds of seeds that you find in flowering plants, which are well protected until they are released. The seeds are often pollinated by special kinds of beetles rather than bees or other insects.
More on cycads: berkeley.edu/cycads.html
There is only one species of Ginkgo in the world today: Ginkgo biloba.
When you look at the fossils of this plant, it seems that there only ever was one kind of ginkgo; the modern plant looks a great deal like its ancient relatives, who date back to the Permian period (a time well before the dinosaurs).
Despite its lack of diversity, the ginkgo once covered huge areas of the world. Now it is only found naturally in Central China.
Most scientists think that flowering trees have been outcompeting the ginkgo, and so the ginkgo has gradually been dying out.
It is sometimes called a living fossil.
At the same time, the tree's beauty has meant that gardeners and park keepers have carefully planted and tended ginkgo trees around the world.
Conifers are close relatives of cycads. They have cones with seeds and they also have woody trunks.
The most noticeable difference is that conifers like cold, northern climates where they can form huge forests that can stretch from one side of a continent to the other.
The typical conifer shape is excellent at shedding snow. They also have many ways of coping with freezing at the cellular level.
Conifers are popular garden plants too. They are evergreen and most grow very quickly.
Some people think of plants and trees as very different. The truth is that trees are plants, just as much as a row of lettuce or a fine rose.
Flowering plants are the most familiar kind of plant for anyone who lives in a temperate climate (not too hot, not too cold).
The thing that makes a geranium so similar to an oak tree is the flowers that they both produce. Flowering plants protect the female parts of the plant inside thick walls of tissue. The male parts of the plant produce pollen, and this needs to burrow its way through this tissue to produce an embryo that then develops into a seed.
Pollen can be transferred from one plant to another by the wind or by insects like bees. Plants that use wind pollination usually have small, drab and inconspicuous flowers. Flowers that use insects for pollination are often big and bright so that the insects can see them from a long way off.
Flowering plants are the plants most able to cope with dry conditions. Cacti can flourish in places where there is no rain for many years at a time.
While flowering trees grow more slowly than conifers, their hard wood is more resistant to insect damage. This means they do better in warmer places.