What part of the plant is involved in reproduction?
Carbon dioxide is generally available to most plants from the air surrounding them.Sunshine is also generally available but insome cases plants have to actively seek it. Plants that live in dense forests do have to compete for light. Noting that most plants grow towards the light, consider the these cases:
Many trees in the forestsgrow very tall to get to the sunlight.
Some rainforestplants climb onothers to reach the sunlight.
Plants that live on the forest floor areadapted to live in the shade and require less sunlight.
To protect themselves, plants cannot run away fromanimals that want to eat them, such as deer, goats,bears, insects, and rabbits. But many plants do haveways to protect themselves. Some plants taste bitter. Some plants havethorns on their leaves or stems.
Some plants are poisonous and causea rash on an animal’s skin. You may befamiliar with the rash caused by poisonivy.
A plant gets water through its rootsand loses water through its leaves .Many of a plant’s adaptations haveto do with getting and retainingwater.
Most plant adaptations seem to have come about because of the plant’s water supply.We will study plant adaptations in:1) Deserts2) Grasslands: savannas, prairie & steppe grasslands3) Forests: rain, deciduous & coniferous4) Tundra.
First, some plant adaptations found in Desert plants.The desert regions shown in brown are dryand generally hot, and often have poor soil thatholds little water.
Plants in desertseither have:1) long roots thatspread out wideand absorb a lot ofwater when it doesrain or2) roots that growdeep into theground.
Desert plantsoften storewater in theirstems orleaves.Cactuses havestems but noleaves. Waxy coating on the leaves or stems reduce loss of water.
Hair or spineshelp shade theplant so it does not lose somuch water.
Next, some plant adaptations found in Grassland plants.The grassland regions can be divided intoSavannas (tropical grassland) shown here inyellow which generally have a warm climateand always have definite wet and dry seasons.
...and the prairie and steppes regions of theEarth. These regions, shown here in yellow,have mainly dry weather, deep fertile soil, andare usually hot in the summer and cold in thewinter.
Roots ofgrassland/prairie grasses extend deep into theground to absorbas much moisture as they can.
Grassland/prairie grasses have narrow leaves which lose lesswater than broad leaves.
The Baobab tree in African grassland has a 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 TropicalRain Forests, shown here in dark green, seldomget below 68 degrees. They also get about 100inches of rain each year and have less than oneinch of top soil.
Tropical rainforest trees haveshallow roots because the soil is sothin. Buttresses and stilt roots helpprop up plants in the shallow soil.
Many rainforest leaves have “drip tips”— a pointed shape which helps drain excess water from the leaf.
Epiphytic orchidshave aerial roots thatcling to the hostplant. They absorbminerals, and waterfrom the atmosphere.
The Deciduous Forests shown here in darkgreen, have four seasons with rain in thesummer 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.
In both the tropical rain forest and deciduous forest the trees have BIG to absorb as much sunlight as possible. LEAVESWater loss through these big leaves is not a problem becausethese regions normally get adequate water.
The thin, broad, light-weight leaves of thedeciduous trees can capture a lot of sunlightto make a lot of food for the tree in warmweather.
Most deciduous trees have deepspreading roots— as wide as the canopy.
When the weather gets cooler, the broadleaves cause too much water loss and canbe weighed down by snow, so the treedrops its leaves. New ones will grow in thespring.
Continuing with adaptations found in the forests of the worldwe consider the coniferous forest shown here in darkgreen.These regions have short summers and long cold winters. 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.
They do not drop leaves Needle-like leaves (needles) all at once in with waxy covering fall. They are kepthelp reduce water loss throughout the year to during freezing make food whenever weather. sunshine and water are available (short summers).
The triangular shape of many conifertrees helps shed heavy snow to savebranches from breaking.
Finally, we look at 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.
This plant grows in a clump to help conserve heat. These tundra plants are low-growing to avoidthe harsh winds.
Plants have shallow roots to absorb the limited water.
We have touched on just a tiny sample ofthe remarkable adaptations plants aroundthe world have made in order to survive.The thing to remember is that plants, aswell as animals, must satisfy their needs inorder to survive, they have to adapt to conditions in their environment.