Plant AdaptationsBy Moira Whitehouse PhD

What do plants need to survive?

• sunlight

• carbon dioxide

• water

• the right temperature

• to reproduce

• protection

As a quick review from our previous lessons, you should remember:

What part of the plant absorbs carbon dioxide?

What part of the plant absorbs water?

What part of the plant is involved in reproduction?

Carbon dioxide is generally available to most plants from the air surrounding them.

Plants that live in dense forests do have to compete for light.

Noting that most plants grow towards the light, consider the these cases:

Sunshine is also generally available but in some cases plants have actively seek it:

Many trees in the forests grow very tall to get to the sunlight.

Some rainforest plants climb on others to reach the sunlight.

Plants that live on the forest floor are adapted to live in the shade and require less sunlight.

Next, we consider a plant’s need to reproduce?

Plants reproduce mainly by flowering seeds or cones.

http://macmillanmh.com/science/2008/student/na/scienceinmotion/Common/SIM.html?Module=../Grade3/Chapter2-LifeCycles/

Let’s use the internet to see at how plants with flowers and cones reproduce.

Many plant adaptations are related to reproduction but we won’t be going there today.

To protect themselves, plants cannot run away from animals that want to eat them, such as deer, goats, bears, insects, and rabbits. But many plants do have ways to protect themselves.

Some plants have thorns on their leaves or stems.

Some plants taste bitter.

Some plants are poisonous and cause a rash on an animal’s skin. You may be familiar with the rash caused by poison ivy.

Many of a plant’s adaptations have to do with getting and retaining water.

A plant gets water through its roots and loses water through its leaves .

Most plant adaptations seem to have come about because of the plant’s water supply. The rest of this presentation will be about how plants have adapted in the regions of the Earth that are defined largely their temperature and by how much or how little water they normally get.We will consider plant adaptations in: 1) deserts, 2) grasslands, savannas, prairie and steppe grasslands, 3) forests, rain, deciduous and coniferous and 4) the Tundra.

First, some plant adaptations found in Desert plants.

The desert regions shown in brown are dry and generally hot, and often have poor soil that holds little water.

Plants in deserts either have 1) long roots that spread out wide and absorb a lot of water when it does rain or

2) roots that grow deep into the ground.

Waxy coating on the leaves or stems reduce loss of water.

Desert plants often store water in their stems or leaves. Cactuses have stems but no leaves.

Hair or spines help shade the plant so it does not lose so much water.

Deep root system or

Next, some plant adaptations found in Grassland plants.

The grassland regions can be divided into Savannas (tropical grassland) shown here in yellow which generally have a warm climate and always have definite wet and dry seasons, and:

the prairie and steppes regions of the Earth. These regions, shown here in yellow have mainly dry weather, deep fertile soil, and are usually hot in the summer and cold in the winter.

Roots of grassland/prairie grasses extend deep into the ground to absorb as much moisture as they can.

Grassland/prairie grasses have narrow leaves which lose less water than broad leaves.

Baobab tree in African grassland has huge trunk to store water

during the dry season

Next, some plant adaptations found in the forests of the world.

There are three forest regions. The Tropical Rain Forests shown here in dark green which seldom get below 68 degrees, get about 100 inches of rain each year and have less than one inch of top soil.

Tropical rainforest trees have shallow roots because the soil is so thin. Buttresses and stilt roots help prop up plants in the shallow soil.

Many rainforest leaves have “drip tips”—a pointed shape which helps drain excess water from the leaf.

Epiphytic orchids have aerial roots that cling to the host plant. They absorb minerals, and water from the atmosphere.

Continuing with plant adaptations found in the forests of the world.

The deciduous Forests shown here in dark green, have four seasons with rain in the summer and rain or snow in the winter.

The temperature varies from hot in the summer to below freezing in the winter. Rain is plentiful, about 30 to 50 inches per year but the trees become dormant in the winter when there is less water available.

to absorb as much sunlight as possible.

In both the tropical rain forest and deciduous forest the trees have BIG LEAVESWater loss through these big leaves is not a problem because these regions normally get adequate water.

The thin, broad, light-weight leaves of the deciduous trees can capture a lot of sunlight to make a lot of food for the tree in warm weather.

Most deciduous trees have deep spreading roots—as wide as the canopy.

When the weather gets cooler, the broad leaves cause too much water loss and can be weighed down by snow, so the tree drops its leaves. New ones will grow in the spring.

These regions have short summers and long cold winters.

Continuing with adaptations found in the forests of the world we consider the coniferous forest shown here in dark green.

Temperature not hot in the summer but very cold in the winter. Moisture is generally good in the spring and summer, but freezes and is not available for the plants in the winter.

Long roots to hold up tall trees.

Needle-like leaves with waxy covering help reduce water loss during freezing weather.

They do not drop leaves (needles) all at once in fall. They are kept throughout the year to make food whenever sunshine and water are available (short summers).

The triangular shape of many conifer trees helps shed heavy snow to save branches from breaking.

Finally, we consider plant adaptations found in the Tundra shown below in brown.

This is a vast, flat, treeless Arctic region of Europe, Asia, and North America in which the subsoil is permanently frozen.

These tundra plants are low-growing to avoid the harsh winds.

This plant grows in a clump to help conserve heat.

Shallow roots to absorb the limited water.

In conclusion, we have touched on just a tiny sample of the remarkable adaptations plants around the world have made in order to survive. The thing to remember is that plants, as well as animals, must satisfy their needs in order to survive, they have to

to conditions in their environment.

adapt