Can you see the difference between wind pollinated and insect pollinated flowers?

Transcription

1 Can you see the difference between wind pollinated and insect pollinated flowers? Age of Students: years Duration: 1 hour Summary Institute: National Botanic Garden of Belgium. Lesson developed by: Jutta Kleber Pollination is a very effective factor in the evolution of plants and thereby an important cause of biodiversity. When discovering the different ways in which indigenous plants are pollinated, insect and wind pollination will be the first items to be discussed. By observing flowers (either living or in images), children can make hypotheses on whether the flowers are wind or insect pollinated. This is an ideal starting point to discover features of wind and insect pollinated plants. Learning outcomes Curriculum links Students know that most indigenous plants are pollinated either by the wind or by insects. Students can recognize a particular plant part as a flower (including cases where it doesn t look like a classical flower e.g. a catkin). Students can describe the function of flowers in reproduction. Students are able to carefully observe various kinds of flowers. Students can describe the visual differences between insect and wind pollinated flowers. Primary school, 3rd grade (10-12 year old): 1. Students can observe using all their senses and can document their observations in a systematic way. 2. Students can, under guidance, test a hypothesis by investigating an observed natural phenomenon. 3. Students can discover similarities and dissimilarities in organisms or materials and classify them by using at least one criterion. 1

2 4. Students can illustrate that organisms are adapted to their environment. Secondary school, 1 st grade (12-14 year old): 1. Students can explain the functions of the following parts of plants: root, stem, leaf, and flower. 2. Students can illustrate with examples that organisms are adapted to their environment. 3. Students are able to carry out scientific research under guidance: a. Formulate a hypothesis, related to question for investigation. b. Collect and organise data, in order to classify, determine or come to a conclusion. Lesson outline Introduction This activity is ideally introduced through a walk in nature or in a park, preferably in late winter and spring (to observe flowering trees) or spring and summer (to observe flowering herbaceous plants). Ask the children to observe flowers. If possible, they may collect flowers. If it is not possible to collect flowers, provide pictures of plants flowering in this season or let the children take photographs of them or accurately draw them. Discuss the following questions with the whole group: Can you explain what pollination is? Do you know how plants are pollinated? Do all plants have flowers? Do all trees have flowers? Next, introduce the students to two symbols: one representing wind pollination and one representing insect pollination. This activity is guided by the teacher. Main activity Divide the class into smaller groups of about 4 participants. Give each group several of the flowers that were collected or the photographs of observed flowers. Ask each group to discuss how they think each flower was pollinated. When the group has decided, the flower (or image) is classified under one of the two symbols (insect or wind). This is an open activity without any interaction from the teacher. The activity can be extended by letting the students research (using books or on line resources) the names of the collected plants and the method of pollination. Plenary The results of this classification activity are presented by each group, giving evidence for their classification, and results are discussed in a plenary session. Did all children have the same results? What errors were made and why? What can the students articulate about the features of wind versus insect pollinated plants? 2

3 Assessment To assess the knowledge, following techniques can be used: 1. Let the children make a concept map about the features of wind versus insect pollinated plants. 2. Give each group a new flower and observe if they can tell how it is pollinated ; check to see whether they use appropriate arguments to defend their opinion. Background information Some features of insect pollinated flowers: Flower features that attract insects: o Large, brightly colored petals. Attention: some flowers that don t look colorful to us do so to insects. That s because insects can see ultraviolet light. o Guide lines for insects to see where the nectoar is o A sweet scent. Usually a short stamen, with anthers firmly attached inside the flowers. Sticky pollen grains that cling to the insect s body. A sticky stigma, so the pollen grains remains in place. Some features of wind pollinated flowers: Small and inconspicuous. Sometimes green or brown in color. They have no scent or nectaries (e.g. flowers of grass plants). The stamen usually has long filaments, with anthers that hang outside the flower. The stigma is large, branched and feathery. Pollen grains are produced in large amounts and are often smooth and light so that they can be carried away by the gentlest of wind currents. Wind pollination is typical for grasses, gymnosperms that produce cones and many shrubs and trees that flower in winter and early spring. 3

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6 List of herbaceous flowers to classify Horse Chestnut Common or Black Alder Apple Hazel Oak Lime 6

7 Sweet Chestnut Common Hornbeam Willow Wild Cherry Silver Birch Hybrid Black Poplar 7

8 Ash Norway Spruce Wych Elm Common Beech Pollination vector: Wind: (11) Common alder, hazel, oak, sweet chestnut, hornbeam, silver birch, hybrid black poplar, ash, beech, Norway spruce, wych elm, Insect: (5) Horse chestnut, apple, lime, willow, wild cherry, 8

9 List of tree flowers to classify Greater Plantain Ragweed Mugwort Crested Dog s-tail Cornflower Rosebay Willowherb 9

10 Rape White Melilot Bindweed Heather Helenium/ Sneezeweed Ox-Eye Daisy 10

11 Timothy Grass Purple Loosestrife Dog Rose Marjoram Pollination vector: Wind: (4) Greater Plantain, Ragweed, Mugwort, Timothy grass Insect: (12) Crested Dog s-tail, Rape, Cornflower, Rosebay Willowherb, White Melilot, Bindweed, Heather, Helenium/ Sneezeweed, Ox-eye daisy, Purple Loosestrife, Dog Rose, Marjoram 11