Mrs. Irwin's integrating science in garden restoration |
Plant
Structure
Plant Structure
From the NGSS standards for disciplinary core ideas for Structure and Function LS1.A: Within cells, special structures are responsible for particular functions, and the cell membrane forms the boundary that controls what enters and what leaves the cell.
Flowering plants consist of four structures (or organs) each with their own functions. The four parts are the following:
Roots: have two major functions, to anchor the plant into the soil and to absorb water and minerals. Most of the plants in our garden have a root system that spreads out in many thin stringy-fibrous strands. The strands are covered in tiny microscopic hairs that increase the surface area of the root. Water moves into the plant in one direction; so the intake only comes through the root system. It is a common misconception that watering the leaves will help the plant take in water. The anchoring system helps the plants to stay-put when faced with wind and water erosion. When we tilled the soil in preparation for planting, there were a lot of root systems in the soil; some of which are no longer with a plant in the soil so they will be broken down by decomposers in our garden to provide the minerals our plants need to grow. Stems: functions are for support, delivery of water and food and some other specialty jobs of specific types of plants. The stem stores food and water as well as delivers food, water and minerals from the roots to the leaves, flowers, and fruits. Green stems can functionally preform photosynthesis since its cells contain chlorophyll. Some of the hummingbird flowering plants in our garden have the green stem Brown stems can store food and water through the winter so that the plant can survive. These plants are called woody plants. In our garden this would be the blackberry, raspberry and returning butterfly bushes. Stems can also store water for the purpose of reserve, especially in areas where rain is less frequent, such as a cactus. The leaves, flower and branching stems grow off of the main stem. Leaves: Are the main site at which the plant makes it's sugar through a process called photosynthesis. This is discussed more in the food and energy page. Plants need sunlight in order to continue growing and making sugar. The white board drawing on the right shows the differences between a growing seed that received light and another growing in a dark closet. The leaves are the site where light energy flows in and molecules flow out, such as water, oxygen, and CO2 through respiration. While water can only flow out, the gas molecules can flow both ways. (this flow can occur in green stems as well). The transport occurs through small pore openings in the leaves called stomata. Below on the right is a microscopic view of stomata on the leaf. While all the plants make sugar, the stevia plant was a choice for the garden because it produces a natural sweetener that I hoped would attract leaf eating animals such as caterpillars and grasshoppers. The plants in the garden have plenty of leaves so we will need to make sure that they are receiving adequate amounts of water and sunlight. The plot that we chose is inclined towards the center so we will receive ground water flow that doesn't get taken up by the plants in the other plots. Some of our plants mentioned not to over-water. Which should work out because our depth sits at 1 m, while there is a point of 2 m so we wont get flooded out. Flowers: When we talk about flowering plants, we refer to the whole plant, not just the flower. All of the plants chosen (on the page directed above) are flowering plants. Flowers are the reproductive part of the plant. I go further into detail below. There are multiple parts to the flower as seen in the diagram on the right. |
Plant Reproduction
From the disciplinary core ideas of Growth and Development of Organisms LS1.B: Plants reproduce in a variety of ways, sometimes depending on animal behavior and specialized features for reproduction.
Flowers have four parts that can be observed by peeling them away in layers. The bud is the outer layer that acts as a protector. We have a tulip plant in our plot, tulip buds will close up overnight and then open again when fully exposed to sunlight. When bud opens you will see the sepals (outer petals) that also help protect the inner workings of the flower as well as supply water to keep the flower from drying out. Next, the main petals supply the colorful attraction and fragrant smells to attract animals who are looking for the sugary nectar in the flower as a food source. We hoped that planting specific dome-shaped flowers would help encourage hummingbirds to our garden but we're also interested in bees, butterflies and other birds.
Within the petals are the stamen, these are the thin stalks with a capsule containing the pollen (which encapsulates the sperm) the stamen are the male parts of the flower. In the middle of the stamen is a taller wider stalk(s) called the pistil. This is the female part of the flower. At the bottom of this stalk is a large sphere containing the ovary with one or more egg cell. These cells will later become seeds.
Not every flower has both male and female parts, the lily below has both. While the flowers with both have the ability to pollinate themselves (with the help of our pollinators), cross-pollination offers more genetic diversity in the population, which is better for the populations survival. When the animals go into the flower to retrieve the sugary food substance, the pollen spores, which are sticky, stick to the bodies of the pollinator animals. Some can be rubbed off on the pistil of the same flower, while other spores can be carried off by the pollinator headed to its next flower in search of food. Wind and water flow also act to move pollen from one flower to the next.
When the pollen is rubbed on the pistil, the pollen will grow a tube down the pistil until it reaches the ovary, the sperm can then travel down the tube to egg cell to create a fertilized egg. The embryo forms the first partially developed root as a small baby plant. The parent plant begin to pack mostly carbohydrates around the the baby plant as a food source. The ovule wall becomes a seed coating protecting the baby plant. We practiced dissecting multiple different types of seeds, all which had a seed coating, carbs source and a partially developed root. The ovary begins to grow bigger, the petals and stamen of the flower fall off. The sepals and the top of the pistil remain and the fruit begins to form. Some of the plants we chose will form berries that have multiple seeds. These are our blackberry and raspberry bushes. The others will form fruits too that may not be edible or appetizing to humans but will help attract or fruit consumers: squirrels, chipmunks, raccoons and birds. Once the fruits are consumed by the animals, they will help disperse the seeds to other locations by leaving them behind in their droppings. Hopefully, if these animals become frequent visitors, some of our seeds will get a chance to return to our garden to grow more plants.
Within the petals are the stamen, these are the thin stalks with a capsule containing the pollen (which encapsulates the sperm) the stamen are the male parts of the flower. In the middle of the stamen is a taller wider stalk(s) called the pistil. This is the female part of the flower. At the bottom of this stalk is a large sphere containing the ovary with one or more egg cell. These cells will later become seeds.
Not every flower has both male and female parts, the lily below has both. While the flowers with both have the ability to pollinate themselves (with the help of our pollinators), cross-pollination offers more genetic diversity in the population, which is better for the populations survival. When the animals go into the flower to retrieve the sugary food substance, the pollen spores, which are sticky, stick to the bodies of the pollinator animals. Some can be rubbed off on the pistil of the same flower, while other spores can be carried off by the pollinator headed to its next flower in search of food. Wind and water flow also act to move pollen from one flower to the next.
When the pollen is rubbed on the pistil, the pollen will grow a tube down the pistil until it reaches the ovary, the sperm can then travel down the tube to egg cell to create a fertilized egg. The embryo forms the first partially developed root as a small baby plant. The parent plant begin to pack mostly carbohydrates around the the baby plant as a food source. The ovule wall becomes a seed coating protecting the baby plant. We practiced dissecting multiple different types of seeds, all which had a seed coating, carbs source and a partially developed root. The ovary begins to grow bigger, the petals and stamen of the flower fall off. The sepals and the top of the pistil remain and the fruit begins to form. Some of the plants we chose will form berries that have multiple seeds. These are our blackberry and raspberry bushes. The others will form fruits too that may not be edible or appetizing to humans but will help attract or fruit consumers: squirrels, chipmunks, raccoons and birds. Once the fruits are consumed by the animals, they will help disperse the seeds to other locations by leaving them behind in their droppings. Hopefully, if these animals become frequent visitors, some of our seeds will get a chance to return to our garden to grow more plants.
Courtesy of the YouTube channel CrashCourse, Hank Green describes not only the structural process of how plants reproduce but also how this process has changed over time. CrashCourse videos can also be accessed through Khan Academy, a great technological resource for learning content areas in mathematics, science and social studies.
Photo used under Creative Commons from mattcornock