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Grade: K to 2 Length: one hour or two, 30-minute sessions Subjects: life science, art, health Topics: identification of plant parts and their functions, introduction to weed adaptations Objectives Exercises in this lesson help students achieve the following objectives: Identify parts of plants (flowers, leaves, stems, roots) on diagrams of weeds and live weed specimens Identify plant parts in common foods Describe the function of plant parts Recognize and explain how the form and function of parts of weeds provide weeds with adaptive advantages over other plants Introduction Most plants are quite literally rooted to their environments. Plants have developed a wide range of adaptations suitable to a sedentary lifestyle. Parts of plants are designed to capture the sun’s energy and convert it to food, obtain and conserve water, protect the plant from animals that might eat it, ensure propagation, withstand a range of climatic conditions, and compete with other plants for resources. Students will learn the name and function of parts of plants. This knowledge establishes a common vocabulary and serves as the basis for future lessons that teach adaptive advantages of weeds, identification of weeds, consequences of weeds’ invasive nature, and effective control strategies. Before teaching this lesson, read the entire lesson and make sure all materials are available. Background Share the following information about parts of plants with students. Adapt the amount of detail to the age, interest, and ability of students. Provide students with illustrations of plant parts (optional). (For illustrations, see the lesson From Seed to Shining Seed.) Plants vary greatly in size and shape, but most plants have the following parts: Leaves – Consist of a blade or lamina, midrib, veins, and a petiole or leaf stalk. Some leaves, such as those on a heather and a pine tree’s or cactus’s needles, are highly modified. Stems and leaf veins contain water carrying tubes (xylem) and sap carrying tubes (phloem). The xylem tissue is in the center, and the phloem is arranged around the xylem. The upper surface of a leaf consists of a waterproof cuticle. The lower surface of a leaf has stomata. Stomata are ventilation holes that take in carbon dioxide and give off oxygen, the gases of respiration. Leaves are the food factories for a plant. Leaves contain chlorophyll, which converts the sun’s energy to food through the process of photosynthesis. Leaves are usually broad and arranged to maximize the capture of energy from the sun. Stems – Provide structure, carry water from the roots to the rest of the plant, and carry food from the leaves to the roots. On many plants, stems also photosynthesize and exchange gases for the plant. Roots – Are generally hidden in the soil. Roots provide plants with minerals and water. Roots are covered with many tiny hairs (root hairs), which increase a plant’s ability to take in water. Only the tip of a root grows. The tip of a root that pushes Invasives: Plants on the Move~~~~~~~~~~~~~~~~~ Weed Identification~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 99 through the soil is covered by a tough root cap. Xylem (water carrying tissue) and phloem (sap carrying tissue) run through roots, with xylem in the center, and the phloem arranged around the xylem. Flowers – Contain the following reproductive organs: Pistil - female part; includes the ovary, style, and stigma Ovary - expands after fertilization and forms the seed or fruit Style - stem-like extrusion of the ovary (A pollen tube extends from the style into the ovary and carries the pollen needed for fertilization.) Stigma - top of the style (The stigma is sticky, and it collects pollen.) Stamen - male part, includes the filament and anther Filament - stalk-like part Anther - tip of the filament, holds the pollen When wind, an insect, or a small animal carries the pollen to the stigma, pollination occurs. After fertilization, the petals of the flower wither while the seeds grow and accumulate food reserves to nourish the embryo plants inside. The petals are usually bright colors to attract pollinators. Petals form a ring or corolla around the reproductive parts. Outside the corolla, the green sepals make up the calyx or outermost part of a flower. Adaptive advantages of weeds Parts of weeds often have special adaptations that enable weeds to spread or out-compete other plants. Examples of special adaptations include fast-growing parts, flowers that create millions of seeds annually for each plant (purple loosestrife), and roots that grow extra long. (Roots of leafy spurge can grow over 17 feet long.) To explore these adaptations in greater depth, see the lesson The Great Race for Survival. Preparation Materials eight, large-size post-it notes potted plant or weed specimen the words head, hand, leg, chest, flower, 1 Print leaf, stem, and root on eight, large-size post-it notes. a student volunteer to stand at the front of 2Ask the room. another student to come forward and 3Ask place the post-it notes with the words head, hand, leg, and chest on the correct part on the first student. the second student places the post-it 4While notes, briefly describe the purpose of each part. For example, “The head protects the brain, which serves as the control center for the body. Through the mouth, which is part of the head, we take in food, and food provides energy to the body. The mouth also allows us to communicate with others.” Make a similar statement for the function of hand, leg, and chest. a student to similarly label the parts of a 5Ask potted plant or weed specimen using the postit notes with the words flower, leaf, stem, and root. Briefly introduce students to the function of these parts while the student places the post-it notes. Activity Materials Diagram of a Typical Plant and Flower Structure worksheets – Have available one copy for each student. the worksheets that have parts of plants 1 Using labeled, show students the Diagram of a Typical Plant and Flower Structure. Discuss parts and their functions. Discuss all parts or some, depending on the age and ability of students. Or draw the illustrations on the chalkboard and label the parts. 100e��������������������������������� Weed Identificationn��������������� Invasives: Plants on the Move each student a copy of the weed 2Give worksheets that have no parts labeled. students to identify the parts in one of the 3Ask following ways, depending on the age and part. Glued-on parts will create a mosaic effect, and the exercise reinforces the connection between diagram and live specimen. Plant parts from live specimens are fragile. For best results, apply a glue stick to the illustration, then gently press the plant part directly onto the tacky area. When students have finished, have them hold up their work, name the weed parts, and describe their functions. ability of students: Have students point to a part and name the part verbally. Conduct this exercise as an entire class or in small groups. Write the name of each part on the worksheet. Working with live specimens or three-dimensional models, have students draw a weed and label its parts. Instruct them to look very closely at the live specimen or model, as if they were a bee crawling all over it to investigate. Suggest that students attempt to fill the entire page with their drawing. Show students some of artist Georgia O’Keefe’s beautifully detailed, close-up paintings of flowers, and share the following quote with them: Conclusion and Evaluation Conclude the lesson by reviewing parts of a weed and the function of each part. Suggest that some parts of a weed often reflect special adaptations that enable weeds to spread or outcompete other plants. For example, some weeds have fast-growing parts, flowers that create millions of seeds annually per plant (purple loosestrife), and roots that grow extra long. (Roots of the weed leafy spurge can grow over 17 feet long.) Evaluate students on their participation in class discussions and the completeness and accuracy of their weed illustration, including a thorough identification of weed parts and an explanation of their functions. Independent Practice and Related Activities Have students color their weed illustration using pigments from live plant specimens. To color with live plant pigments, rub the appropriate plant part onto the illustration. For example, rub leaves onto leaf areas of the illustration and petals onto petal areas. Friction with the paper will break down the organic material, and the pigments will bleed directly onto the paper. Remove organic residue by lightly brushing the surface of the paper with your fingertips. Discuss the function of plant pigments. Have students dissect or pull apart live weed specimens. If possible, use the same specimen shown in the illustration. Glue stems, roots, leaves, and flowers directly onto the illustrations within the appropriate margins for that “A flower is relatively small. Everyone has many associations with a flower – the idea of flowers. You put out your hand to touch the flower – lean forward to smell it – maybe touch it with your lips almost without thinking – or give it to someone to please them. Still – in a way – nobody sees a flower – really – it is so small – we haven’t time – and to see takes time, like to have a friend takes time. If I could paint the flower exactly as I see it no one would see what I see because I would paint it small like the flower is small. So I said to myself – I’ll paint it big and they will be surprised into taking time to look at it – I will make even busy New Yorkers take time to see what I see of flowers.” – Georgia O’Keefe Prepare small bowls with a selection of edible plant parts, such as celery, carrots, fresh spinach leaves, radishes, broccoli florets, pumpkin, and sunflower seeds. Ask students to identify each food as a leaf, root, stem, flower, or seed and name its function. Students should share plant-part snacks by asking for a plant part name, not common name. For example, “Please pass the stems,” or “Please pass the orange roots.” Invasives: Plants on the Move~~~~~~~~~~~~~~~~~ Weed Identification~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 101 Vocabulary adaptation, flower, form, function, leaves, pigment, root, stem Resources Proctor, John, and Susan Proctor. Color in Plants and Flowers. New York: Everest House, 1978. Spellenberg, Richard. National Audubon Society Field Guide to North American Wildflowers, Western Region. 2nd ed. New York: Knopf, 2001. National Science Education Standards As a result of their activities in grades 5 to 8, students should develop abilities in and an understanding of the following areas: Life Science – Content Standard C: characteristics of organisms, life cycles of organisms, organisms and environments For three-dimensional models of weed specimens, contact the Center for Invasive Plant Management, 733 Leon Johnson Hall, MSU Bozeman, P.O. Box 173120, Bozeman, MT 59717-3120; 406-994-6832. [email protected], www.weedcenter.org 102e��������������������������������� Weed Identificationn��������������� Invasives: Plants on the Move Diagram of a Typical Plant Invasives: Plants on the Move~~~~~~~~~~~~~~~~~ Weed Identification~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 103 flower root bud stem leaf 104e��������������������������������� Weed Identificationn��������������� Invasives: Plants on the Move Invasives: Plants on the Move~~~~~~~~~~~~~~~~~ Weed Identification~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 105 petal stigma style ovary anther 106e��������������������������������� Weed Identificationn��������������� Invasives: Plants on the Move