World Builders™
World Builders™
Session Eight --  Land Plants  
Session Eight  -- Land Plants  

How to Design Your Land Plants
How to Design Your Land Plants


Communities of eukaryotic algae began to grow in the water.

Part One: Choose One of Your Water Algae to Work With

Design Step 1: Choose a water plant

I have chosen the scrubber, a low-growing alga that clings to rocks in the ocean.

The scrubber grows in shallow water and is sometimes left in the air at low tide.


Design Step 2: Show what the organism looks like on land.

The scrubbers' mass of cells has grown to be more sponge-like so that it can hold onto rain water. I call these algae mats.

These algae have no roots or vascular structures. When there is no rain they dry out and die, but some of the cells become dormant as tough walled unicellular cysts. These begin to grow again when they get wet, and the dry remains of the dead cells hold the water around them.

The tiny dry cysts can also be picked up and blown by the wind during storms. Some of them later develop into new plants.

Mats are able to survive on land in areas of heavy rainfall (future Rain Forest biome).

Design Step 3: Show additional adaptations.

See what can happen in a few million years! Some of the mats have become shaggy mats. Parts of them extend out past the rocks and contact the soil, but they don't really have any roots yet. However, the cells on the bottom do poke down into the ground a fraction of an inch, and water moves through the clump by capillary action. When cells form long strings lying side by side the water transport is more efficient.

Shaggy mats continue to live in areas of high humidity and heavy rainfall.

Part Two : Diversify into More Biomes

Biome One: See low-growing plants above.

Biome Two: Adapt Plant to what could become a Grasslands Biome

Adaptation Step One: Think about the Biome

I have chosen the climatic rigion that could become a Grassland Biome.  My planet does not have any grass yet 00 that will take much longer.

A Grassland Type of Biome has intermittent rain and often has long, freezing winters.  The new plants will need to store water more efficiently, protect the reproductive cysts from cold, and anchor themselves more firmly to resist the wind.

A thicker plant mass can do these things: I will make the plants mound up. They will need better ways to hold onto the ground, too.

Adaptation Step Two: Create and describe the plants

Here is how I created the new plants, the hay stacks.


I began with the shaggy mat picture .

I filled in the spaces with green.
I added fuzziness with the spray can.

I used copy, paste, and stretch to make a number of different plants.

These shaggy mats have adapted to this biome by becoming heaps of vegetation. I call them haystacks.

These plants hang onto the ground by projecting cells that go into the soil. These projections are not really true roots, although they do pick up a little moisture. Perhaps they will evolve into roots.

These plants are dense mats of vegetation. The inside of the mounds appears to be dead, but it absorbs and holds water. There is some water transport between the cells.

The dense matted structure also protects the cysts from dehydration by the cold winter winds. The plants die in the cold, but they have "learned" to form cysts in response to cold as well as dry weather.

Haystacks reproduce by starting up from any living broken piece (vegetative reproduction) and by having their cysts blown to new places by the wind.

Additional Adaptations for the Haystack Family
 (Optional but easy!)

Millions of years have passed. The climate is becoming wetter. Trees are encroaching on the grassland. There is some shade on the ground where the haystacks are.

Some of the haystacks have true roots now. This allows them to grow into taller mounds. I call them high hays .

These high hays are a mass of tough and fibrous tangled stem-like strands. These strands are interwoven, holding the plant together.

The cells on the insides of these high hays sometimes grow in parallel groups. This provides places where water can be transported by capillary action. These groups of cells may be the beginnings of a vascular system. With increasing rainfall, the outer cells can stay alive even on such a tall plant.

Biome Three: Adapt Plant to Tropical Forest Conditions

 Adaptation Step One: Consider the Tropical Forest Biome.

This biome is wet, warm, and humid, but the competition for light is fierce. The shaggy mats must find some way to get a share of the light.

If they form thin mats with adhesive cells under the green cells they will be able to climb trees, especially if they form cysts everywhere along their growth.

 Adaptation Step Two: Take a Primitive Clump of Shaggy Mats


Change size, flatten, stretch.

This is a soft, loose mass of cells that climbs over anything in its path.   It can even climb up trees and hang down from their branches.


Here are some cells from the bottom of this Shawl Plant. You can see that the base of each one has a little brown part that can grip the surface that it is on.


Part Three : Some Ways to Report Your Results

1. Use a Table

Notice that I have given the plant's parentage with the name: grandparent/parent/plant


The Development of Land Plants





 Special Adaptations



1/4 inches to about 2 inches clings to stones in shallow and tidal water and to rocks in heavy rain areas cells cling to rocks with small primitive structures
reproduction by cysts



1 to 2 inches clings to rocks in rain forest type environments Thicker mats soak up water
reproduction by cysts and broken pieces

Shaggy Mats

/mats/ shaggy mats

2 to 4 inches heavy rainfall and humidity

will become rain forest one day
Some contact with soil, water moves by capillary action in the clumps
reproduction by cysts

 Hay Stacks

/mats/shaggy mats
/hay stacks

 4 inches to 30 inches Grassland biome: rain 10-30 inches
cold winters, wind
special structures grip the soil
mounds of plant strands hold water
reproduction by cysts

 High Hays

/mats/shaggy mats
/hay stacks/high hays

 30 to 60 inches Edge of Forest Environment Tangle of plant strands creates platform for continued upward growth
reproduction by cysts


/mats/ shaggy mats

 1/2 to 2 1/2 inches

flat, broad mats

Interior of tropical rain forest Growth can coat rocks, trees, branches in vine-like growth habit
gripping structures on bottom of mat
reproduction by cysts


2. Use a Diagram to Show Evolutionary Relationships

This chart shows how the life forms are related.

The new species that develop from a parent species are shown going down, for example, the scrubber is the ancestor (parent) of the mats and then the shaggy mats.

Species that develop from a common ancestor are shown side by side, for example, both haystacks and shawls evolved from the shaggy mats.

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© 1996,1997, 1998, 1999, 2000, 2002, 2003 2005.   Elizabeth Anne Viau. All rights reserved. This material may be used by individuals for instructional purposes but not sold. Please inform the author if you use it at .