1. The stigma is the covering of the ovary and each pollen grain landing on the top of the stigma makes a tube through the stigma into the ovary underneath ending in an ovule.

The contents of each pollen grain empty down the pollen tube into the ovule. Each fertilised ovule grows to become a seed.

Above is a graphic of a poppy flower without the petals and cut in half to show the reproductive parts.

This may help with the flowers you examine in the classroom and there are many books which show this sort of drawing for other flowers.

It is probably a good idea to give each child a small tray such as those which come with packaged food for them to keep their flower parts in.

Worksheet D27a (G) can be used to record the parts of the flower and their functions.

Early Autumn is probably a good time to do this lesson. Worksheet D27b (G) is a table which the children can fill in with the things they learn about the types of seed. It is much better to have real examples for the children to look at and many are available even in urban sites. Some useful examples might be ;-

Animal Internal - (The animal eats the fruit and although the fruit is digested, the seeds pass unharmed through the gut and are passed out wherever the animal wanders.) : any berry.

Animal External - (The seed sticks to the coat of the animal and gets knocked off or groomed off at some place away from the parent plant.): beech nuts, burdock, cleavers (the last named also known as "Goose Grass", or "Sticky Willy" depending on where you live).

Wind dispersed - (The seed is able to fly away from the parent plant and be carried on the wind to a new resting place.): dandelion, thistle, poppy, grasses, sycamore.

Self explosive - (The plant has some means of exploding the seed pod - often to do with moisture content - and the seeds are flung far and wide): members of pea family, Balsam etc.

The children should understand that it is an aid to survival if plants disperse their seeds in space (also in time - which is why many are dormant for a while) because otherwise all the new plants would be growing on the same piece of land and they would quickly become choked and few would survive.

3. Pollination is the term used to refer to the process whereby the pollen (male part - equivalent to sperm in animals) is introduced into the ovary to join with the ovules.

Pollination is carried out by insects, animals and the wind. In some plants, the pollen and the ovules are ready at different times in order to prevent self-pollination. In other plants they are all ready at the same time to maximise the chance of pollination.

See The Bee's Knees.

The sole purpose of flowers is to reproduce. Various different flowers use different tactics for their chosen method of pollination. Plants which are pollinated by animals use colour, scent and design to attract carriers in. Some plants have special lines on the flowers which are invisible to the human eye but are like runway lights to a bee! Other plants produce specially shaped tubes for birds such as humming birds to dip into with their very long tongues.

The reward for the carrier is a drink of nectar - a sugary liquid at the base of the flower. Bees use it to make honey and for many species it is their main or sole source of food. That is not practical in Britain since most plants cannot flower in winter.

The carrier enters the flower and in order to reach the nectar they must rub up against the stamens and/or the stigma. Pollen becomes stuck on their fur/skin/feathers/ beak / body and is carried to another plant where it rubs off onto the stigma. The pollen tube grows and pollen travels down the pollen tube and into the ovary.

As the seeds develop the fruit ripens. In poppies, the outside wall dries up and holes appear at the top. The seeds break away from the walls inside the fruit. They fall out through the holes near its top when the poppy is blown by the wind. There are many variations on this development and you can look at some of these by examining different types of fruit.

The children could keep a written or picture diary of their plant and measure its growth. Worksheet D27c (G) can be used as a cut and stick exercise for plant life-cycles.

The Bee's Knees

This science lesson with my Year 5 class where I did my training looked at ; pollination and fertilisation. To start, we revised the biological terms for the male and female parts of flowers by group discussion. Then I pinned a large drawing on the board to show the various parts of a basic flower. I attached pot-pourri to the stamen to represent pollen, and used a small stuffed insect toy on string - meant for cats to play with but it represented the insect perfectly. I attached tape to its back and showed the children how the insect enters the flower and brushes past the pollen as it makes for the nectar, at which point I attached some of the pot-pourri to the toy’s back. The insect then left the flower with pollen on its body. I stuck another large flower drawing on the board and used it to show how pollen is released into the stigma/style.

I "flew" the insect towards the nectar of the second flower. It brushed past the dangling stigma, which collected the pollen from its back. The pot-pourri  was then removed from the toy and stuck on the stigma of the flower.

The large-scale diagrams led to an excellent discussion during which the pupils asked intriguing and pertinent questions, such as: "How does pollen actually stick to the insect?" The concept of wind pollination also arose naturally along with development of the seed in the ovary.

As a reward for all of their hard work, I gave each pupil a small fridge magnet of a bee.

Nathan Davies, training at John Bunyan Junior School, Braintree, Essex

From Teacher' Tips, Teacher Magazine, TES June 13 2003
 

Growing radishes in the classroom

Radishes are fast growing and can be taken through their complete cycle on the classroom window sill.

Use discarded film canisters (most film processing shops will have a few and may be happy to keep them for you ) and make a hole in the bottom. Use a small strip of cloth or ribbon threaded through this hole as a wick. Fill the container with peat and sow one or two radish seeds in each pot.

Put all the film canisters into ice cream tubs which have several sheets of kitchen towel in the bottom. You should be able to get ten or twelve canisters in each tub. Add water to the tubs so that the kitchen towel is wet. Water will be drawn along the fabric wick into each canister and so keep the soil moist.

Keep the kitchen towel moist but not soaking. Watch the seedlings grow and if more than one grows in a canister then pull out the weaker looking of the two. The plants should grow fairly quickly on a warm windowsill and will flower. Use a clean paintbrush as a ‘bee stick’ to pollinate the flowers and collect the seeds they produce.

 

This is an allergy to pollen. It is most commonly seen in summer and is often caused by grass pollen. Hayfever can occur at other times of the year. In spring the culprit may be tree pollen and in autumn can be due to weed pollen. The nose and the eyes are the places most commonly affected by the tiny pollen grains. In some people the hay fever may lead to asthma.

Using the information from the National Asthma Campaign see if you can list the symptoms of hay fever. Some people in your class may be able to tell you about their own symptoms.

Teacher/Technician Notes  

Mineral Salt Solution for Germination of Pollen Grains (makes 1 litre)

Sugar Solution for Germination of Pollen Grains when using Mineral Salt Solution

Sugar solution to be used on its own for the germination of pollen grains

Stain for pollen grains