The secret of the winter flowers

It’s January 1st and the floor of the wood is covered with fresh new leaves, growing in dense patches. The first flowers are starting to open. Within a week, the air is scented with a sweet fragrance. This is the winter heliotrope, which is just as much at home in Nowhere as it is in its native North Africa.

The winter heliotrope was probably brought to Britain by Victorian gardeners.

 

We have a large Victorian estate called Tyntesfield down the road, so originally it could easily have come from there. The plant has a big secret: its flowers are just for show!

The winter heliotrope is unusual because it has separate male and female plants. As far as we know, the Victorian gardeners only imported male plants into Britain, because they liked the showy flowers and its rich scent. So, although the flowers make good pollen, there are no female flowers available to receive it. These plants cannot make seeds.

How do the plants reproduce, if they  cannot make seeds?

What is its big secret?

 

 

 

 

Below the soil the plant has a special underground stem, called a rhizome. During the year the rhizome stores food ready for the wintertime. Then, early in the new year, it grows new leaves and flowers.

During the summer the rhizomes grow so large, that they eventually break off and become new plants. This is a different way of reproducing, called vegetative reproduction. The plants are all clones, they have the same genetic information, which means that they all flower at more or less the same time.

So good is the winter heliotrope at growing in this way, that the plant is seen by some gardeners as an uwanted pest. It seems to grow well in Nowhere Wood, where it grows undisturbed.

1. What do you think are the advantages of being able to reproduce vegetatively, without making seeds?

2. Are there any disadvantages to having plants that all have the same genetic information. Is variation needed for the survival of plants?

Fruits of the autumn

Autumn is the time for fruits to become ripe enough for animals to eat. This time last year, Nowhere Wood was full of ripe acorns and the squirrels and birds had a heyday. This year, there are no acorns, at all. Life is uncertain, in Nowhere Wood.

Somewhere, inside a fruit, is a seed and seeds contain new lives – the next generation of the woodland plants.

These fruits are blackberries. The seeds are found inside the berries. They are tiny, with hard tough seed coats.

Birds, especially blackbirds and thrushes, love to eat blackberry fruits. In doing so, they help the plant to spread its seeds away from the wood.

 

To survive, the blackbirds need the blackberry fruits and the blackberry plants need the blackbirds.

  1. Think about what happens to the seed when the fruit is eaten by a blackbird.
  2. How does the blackbird help the blackberry plant to spread its seeds away from the wood?

The secret of the winter flowers

All change!

When you next look into a mirror ask yourself if you are the same person as you were yesterday. Well, of course you are.

Even people who last met you ten years ago can still recognise you and call you by your name. Although they might add, “My, how you have grown!”

And yet, if we could see under your skin, we would find that you are not the same. One of the biggest mysteries in biology is how we can change all of the time, whilst still staying the same.

Your skin cells live for about two weeks, so every month they are completely replaced. Red blood cells live for about 100 days and about two million are made in your body in every second.

Some of the chemicals in your cells exist for only minutes or seconds.

There is an energy store called ATP, which is needed for muscle contraction. ATP is made and broken down within 15 seconds.  Cells need glucose to make ATP and this explains why muscle cells need a continuous supply of glucose to stay alive. This comes from our food.

Even large organs, like the liver, are replaced regularly. You grow a new liver every year. The cells in the alveoli of your lungs are renewed every eight days. Even the bone cells in our skeleton are replaced every three months. Your entire skeleton is remade every ten years.

 

So, when your friend sees you after ten years and calls out your name, there is not a single part of your body that was the same as when you last met. You have been completely remade and remodelled. And the same is true of your friend.

 

So, how can this be? New cells are made when one cell divides to make two cells. The information in the genome is copied before cells divide, so the new cells always receive the same information as the old cells.

The new cells use this information to grow bigger and to develop. So, you stay the same because of how your new cells use the information in their genomes.

Living organisms are alive because they actively remake themselves. No man-made machine can do this. Which is, perhaps, just as well.

  1. In what ways have you changed in the last ten years?
  2. In what ways have you stayed the same?
  3. Why do need to eat food everyday?

A year in the life of a sugar factory

Life is a relay race

This story continues the adventures of the ferns in Nowhere Wood. The first part of the story is Climbing the walls.

The genome of the fern contains essential information that the fern needs to grow and  make new cells. At different times the fern produces spores, sperm and eggs and the two forms of the plant. The genome contains information on the growth of each of these stages.

The information in the genome is the same in every cell of the fern because an identical copy of the genome is found inside the nuclei of all the cells of this fern at every stage of its life.

The genome is found in the nucleus of each cell.

The genome is divided between a number of chromosomes. The diagram shows the genome of the Adder’s tongue fern. It has about 1440 chromosomes. This is the largest number of chromosomes of any organism in the world!

Fern genomes are larger than the genomes of other organisms, because they contain the information the fern needs to grow spores, sperms and eggs as well as the two forms of plant.

The genome contains the secrets of how to be a fern and how to move forward in the adventure. This information has been copied and passed on to each generation of ferns, ever since the first ferns evolved about 390 million years ago.

 

 

Life is like a relay race: genetic information is passed on from one generation to the next in the genomes of sperms, eggs and other gametes.

These ferns are having risky and uncertain adventures in time as well as space. If the secret information is not passed on correctly, then the species may become extinct. History shows us that most species that have ever lived on Earth are now extinct.

    1. Why do you think it is essential that the genetic information from parents to offspring is copied accurately?
    2. Why do you think the fern genome is so large, compared with other types of plant?

All change!

Climbing the walls

A hundred years ago, Nowhere Wood was a sandstone quarry, and there is still a cliff face at the end of the wood.
How can this hart’s tongue fern grow on a vertical cliff face about two metres from the ground.

That is quite an adventure in time and space. This story explains how this fern can climb walls.


Ferns are an ancient group of plants, first appearing on Earth about 390 million years ago. That’s about 260 million years before the emergence of flowering plants.

Like fungi, another ancient group, ferns produce spores. They are the brown dots on the underside of this fern leaf. Spores are light and float in the air like particles of dust.

One spore floats up to a small crack in the rock face. Rainwater and the decaying remains of a leaf have formed a sticky, jam-like, humus inside the crack.  The spore sticks to the humus and germinates, developing into a tiny little plant, about 10 mm long.

This is a fern, but it is not the mature adult form. It has tiny roots that grow into the humus, drawing nutrients from it.
This small plant is called a gametophyte because it makes gametes for sexual reproduction. Gametes are sperm and egg cells. 


These gametes will come together to make the adult fern on the surface of the tiny gametophyte.

The gametophyte makes many small sperm that swim in the water on the surface of the plant. They swim towards eggs, which are much larger. This photograph shows a fern sperm fertilising a fern egg.

The sperm and the egg join together. A single cell is produced that will grow into the adult fern. Eventually this fern will make spores of its own.

This may sound like a long-winded and complicated adventure, but it seems to work well, because there are so many ferns in Nowhere Wood.

The fern exists in several different forms during its adventure: spores, eggs, sperm, gametophyte and adult plants. What do they have in common?

Each of these forms is made of one or many cells. Each cell contains a nucleus, and inside each nucleus is a genome. Genomes contain information. The information in the genome is the same in all of the different forms of the fern.

The genome contains the secrets of how to be a fern and how to move forward in the next step of the adventure.

  1. The fern exist in several different forms during its adventure: spores, eggs, sperm, gametophyte and adult plants. Think why is important that the genome in every form is the same? 

Life is a relay race