Peek inside a flower this spring to see how one of the most successful surviving plants on earth does it.
Caution: This activity involves the use of a sharp blade, have an adult present to help you.
What you need
A flower
A knife or a blade – get an adult to help you with this cutting tool
A magnifying glass if you have one
A pencil and some paper
What to do
Go outside into the Spring air and find yourself a flowering plant (avoid daisies, roses and irises as it is hard to see their reproductive parts). Pick just a few flowers (don't be greedy) and take these back to a well lit bench.
Look at your flower carefully and then draw it. Try labelling the petals and the sepals (have a look at our diagram first).
Very carefully, cut down the middle of the flower, so the flower is in two halves. Try to get a nice, even clean cut. Draw what you can see inside the flower.
Have a look at our diagram and see if you can label the sepals, stamen, stigma, style and ovary of your flower. Did you know there was so much in one flower?
Look inside the ovary – can you see the ovules. These develop into seeds when they are fertilised.
Note: All flowers are different and they will not all look like the classic flower in the diagram – especially some of our native flowers.
What's happening?
Flowers are the success story of the plant world. The first flowering plants (angiosperms) appeared in the world at least 132 million years ago, maybe more, and are the largest and most diverse plant group, making up 80 percent of all green plants.
The flower is the reproductive part of an angiosperm. Some flowers can self pollinate, but most cross-pollinate (pollinate with another plant or flower). Once the pollen sticks to the stigma, it starts an impressive descent. It first germinates and then extends a tube to grow down through the style into the ovary. Once there, it discharges two sperm cells into the embryonic sac (this is inside the ovule). Both sperm cells fertilize cells in the embryonic sac, in a process known as double fertilization. Once fertilized, the ovule develops into a seed.
The fruit then comes along – a fruit is a mature ovary. Fruits protect the seeds and aid in their dispersal. Fruits like apples and pea pods are examples of a simple fruit as they have developed from a single ovary. A luscious raspberry however, is an aggregate fruit, as it comes from several ovaries that were part of the same flower. For wild and wacky reproductive antics try the pineapple, as they develop from separate flowers entirely.
There is a lot going on in your flower! Here is an overview of its parts.
Stamen: Male part of the flower that produces pollen. The stamen is made up of the anther at the top, which makes the pollen, held up by the filament.
Carpel: Female parts of the flower. Made up of the sticky stigma (an exposed part where the pollen first touches), the style (the tube the pollen travels down), the ovary and the ovules (which develop into seeds after pollination).
Petals: Bright coloured, often using colours invisible to the human eye such as ultraviolet, and perfumed attractants to insects.
Sepals: This circle of modified leaves encloses and protects the flower before it opens.
Did you know that the tallest flowering plant in the world is the Victorian eucalypt, Mountain ash (Eucalyptus regnans)?
Pollinators are very important to flowering plants; and insects, birds, animals and the wind all can be pollinators of angiosperms. In many cases the relationship between the plant and its pollinator is a very close one, and co-evolution has made the two pretty much indispensable to each other. The pollinator usually relies on the plant as a food source, while the plant could not reproduce without the animal transferring its pollen.
This co-evolution is responsible for much of the diversity of flowers. Flowers are often pollinated by just one animal, like a bee, beetle, bird or bat, and the colour and fragrance of a flower is usually intended to suit the pollinator's senses of sight and smell.
Applications
Flowering plants provide nearly all of our food. Not just fruit and vegetables but corn, rice, wheat and all the flowering grasses that provide feed for stock. Understanding these plants and their pollinators is vital for our full bellies. It is also important to conserve and protect the diversity of the plants we use for food, as crops are vulnerable to natural and human made environmental disasters. One way to do this is to create a seed bank – a big seed library where seeds are stored and protected for future use.
