Lesson 13 Which way is up?
Completion requirements
Other Plant Responses
Plants do not only respond to light and gravity, there are other stimuli they respond to as well.
A13.10 Pea Plant sending out tendrils
Plants also respond to touch, temperature, chemicals, water, and length of darkness or light. Not all plants respond to all of these stimuli, but most respond to more than just light and gravity. For example, climbing plants such as peas or clematis
will send out tendrils looking for something to grab hold of. Once they find something strong, they will wrap the tendrils around it so the plant can climb up. This is why climbing plants are often seen climbing rock walls, fences, or trellises.
Many plants will use these other stimuli as a signal for when their needs are met and they can begin to flower or produce fruit. For example, plants that flower in the winter often need a certain amount of time in darkness every day in order to flower. Some examples of these plants are poinsettia or a Christmas cactus. Other plants need a certain amount of time in light every day in order to flower.
Many plants will use these other stimuli as a signal for when their needs are met and they can begin to flower or produce fruit. For example, plants that flower in the winter often need a certain amount of time in darkness every day in order to flower. Some examples of these plants are poinsettia or a Christmas cactus. Other plants need a certain amount of time in light every day in order to flower.
Did You Know?
The mimosa plant responds to touch in a unique way. When you brush against this plant, the leaves collapse together and the stem bends away from the touch. This is a defense mechanism that protects the plant from damage from
wind
or animals passing by. If you are interested in watching this response, please go to the following link.
Did You Know?
A13.11 A banana plant
An ornamental banana plant must leaf out 47 times (produce 47 leaves) before it will produce any fruit. This is how the plant makes sure it is strong enough to support the production of fruit.
Read This
Please read page 328 in your Science 10 textbook. Make sure you take notes on your readings to study from later. You should focus on other stimuli that plants respond to.
Remember, if you have any questions or you do not understand something, ask your teacher!
Practice Questions
Complete the following practice questions to check your understanding of the concept you just learned. Make sure you write complete answers to the practice questions in your notes. After you have checked your answers, make corrections to your responses (where necessary) to study from.- Why do you think some plants require a stimulus to signal them to begin producing flowers or fruit?
A stimulus is needed to signal the production of flowers as some plants want to make sure they are able to support the flowers. They wait until they know they have enough stored energy to produce the flower or fruit as it takes lots of energy
to create these. Flowers and fruits are needed as those create the seeds that produce the next generation of plants. Plants also want to make sure they produce the flowers or fruits at a time when those potential seeds can thrive.
- Can you think of other plants that respond to stimuli other than light and gravity?
Carnivorous plants (Venus flytrap, pitcher plant) respond to touch. Other plants, such as tulips, hyacinths, and daffodils, will not start to grow until they have gone through a period of cold weather. Still other plants require heat to start
growing. In the mountains, there are some types of pine cones that will not release their seeds until they have been through the heat of a forest fire. An example of this would be the lodgepole pine or jack pine.