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The Green Machine Understanding the Seedless Vascular Plants 21 The Green Machine Understanding the Seedless Vascular Plants 21 To the Instructor The seedless vascular plants include several plants with which students are familiar, such as ferns. These plants can serve in “hands-on” experiments to introduce students to the seedless vascular plants. An understanding of this chapter is necessary to understand plant evolution. This chapter can easily be modified to teach along with other chapters on plant diversity. The instructor can pick and choose activities from these chapters to meet the needs of the students. Topics for Discussion 7 At the beginning of this lab, review the objectives to the chapter. If this chapter is taught with other plant diversity chapters, cover the objectives and material for the other chapters. 7 Discuss the classification and basic evolution of the seedless vascular plants. 7 Discuss the phyla of the plants included in this chapter, providing specific examples, natural history, uses, life history, and anatomical information. 7 Discuss and bring in local specimens or photographs of the plants discussed in this chapter. 7 Discuss the environmental, industrial, and medical importance of the seedless vascular plants. Total Estimated Completion Time: 2 hours, 30 minutes 1 EXERCISE 21.1 Phylum Lycophyta Estimated Exercise 21.1 Completion Time: 40 minutes Procedure 1 Macroanatomy of Lycopodium Estimated Procedure 1 Completion Time: 10 minutes Materials ❏❏ Dissecting microscope ❏❏ Living or preserved specimen of Lycopodium (Carolina Biological 156990) ❏❏ Colored pencils Procedure 2 Microanatomy of Lycopodium Estimated Procedure 2 Completion Time: 10 minutes Materials Strobilus ❏❏ Compound microscope ❏❏ Prepared slides of Lycopodium (Carolina Biological #’s 299818 and 299836) ❏❏ Colored pencils Procedure 3 Macroanatomy of Selaginella Estimated Procedure 3 Completion Time: 10 minutes Materials ❏❏ Dissecting microscope ❏❏ Living or preserved specimen of Selaginella (Carolina Biological #157016) Embryo (2n) ❏❏ Colored pencils growing from megagametophyte (n) (which develops partially within the megaspore wall) Chapter 21 | The Green Machine: Understanding the Seedless Vascular Plants 2 Microsporophyll Zygote (2n) Microsporangium Fertilization Sperm (n) Meiosis Megasporangium Meiosis Microspores (n) Endosporic microgametophyte Archegonium with sperm (n) with egg (n) Rhizoids Megaspores (n) Archegonia Megaspore wall “Germinating” to form rhizoids and gametangia Spore wall Megagametophyte Procedure 4 Microanatomy of Selaginella Estimated Procedure 4 Completion Time: 10 minutes Materials ❏❏ Compound microscope ❏❏ Prepared slides of Selaginella (Carolina Biological #’s 299854 and 299878) ❏❏ Colored pencils Check Your Understanding 1.1 Describe several uses of Lycopodium. Medically, it has been used in homeopathic remedies including as an emetic, as a baby powder, and as a worming agent. At Christmas, ground pines are used for decorations. Lycopodium spp. spores have been used in controlled explosions, such as early photographic flashes.Lycopodium spp. have been used as a stabilizer in ice cream. The spores have also been used as a fingerprint powder and in fireworks. 1.2 Where can one findSelaginella ? Selaginella spp. appear to creep along the ground with simple, scalelike leaves on branching stems from which roots also arise. It is called resurrection plant because of its habit of curling into a tight ball and turning brown when dry and opening out flat and turning green when water is again available. 1.3 Compare and contrast megaspores and microspores. The megaspores are large spores that develop into a female gametophyte, which eventually produces egg cells. The megaspores are fertilized by a sperm cell produced by the male gametophyte developing from the microspore. Chapter 21 | The Green Machine: Understanding the Seedless Vascular Plants 3 EXERCISE 21.2 Phylum Psilotophyta Estimated Exercise 21.2 Completion Time: 20 minutes Procedure 1 Macroanatomy of Psilotum Estimated Procedure 1 Completion Time: 10 minutes Materials ❏❏ Dissecting microscope or magnifying glass ❏❏ Living or preserved specimen of Psilotum if available (try university greenhouse) ❏❏ Colored pencils Procedure 2 Microanatomy of Psilotum Estimated Procedure 2 Completion Time: 10 minutes Materials ❏❏ Compound microscope ❏❏ Prepared slides of Psilotum (Carolina Biological #’s 299176 and 299181) ❏❏ Colored pencils Check Your Understanding 2.1 What is the common name for members of phylum Psilotophyta? Phylum Psilotophyta is a rather obscure phylum of plants known as the whisk ferns. 2.2 Where is Psilotum usually found? Psilotum spp. are commonly found in warm moist regions in the southern United States. 2.3 Describe several distinguishing features of phylum Psilotophyta. The small plant has no leaves or roots and a dichotomously branching green stem with small scales that bears bright yellow synangia on lateral branches. A synangium is formed from three fused sporangia on short lateral branches. Psilotum spp. are homosporous. A horizontal rhizome gives rise to an aerial stem. Chapter 21 | The Green Machine: Understanding the Seedless Vascular Plants 4 EXERCISE 21.3 Phylum Sphenophyta Estimated Exercise 21.3 Completion Time: 30 minutes Procedure 1 Macroanatomy of Equisetum Estimated Procedure 1 Completion Time: 10 minutes Materials ❏❏ Dissecting microscope ❏❏ Living or preserved specimens of Equisetum, one branched and one unbranched (try local nursery) ❏❏ Colored pencils Answers to Procedural Questions 2a Compare and contrast the external anatomy of the branched and unbranched forms of Equisetum. Branched species of Equisetum spp. have whorl of branches imitating from each node, and other unbranched species have nodes without whorls. 2b Describe the texture of the stem. The stem is rough with parallel ridges. Procedure 2 Microanatomy of Equisetum Estimated Procedure 2 Completion Time: 10 minutes Materials ❏❏ Compound microscope ❏❏ Prepared slides of Equisetum (Ward’s Science #’s 914814, 914818, and 914821) ❏❏ Colored pencils Chapter 21 | The Green Machine: Understanding the Seedless Vascular Plants 5 Procedure 3 Calamites Fossils Estimated Procedure 3 Completion Time: 10 minutes Materials ❏❏ Dissecting microscope or magnifying glass ❏❏ Fossil specimen of Calamites (Ward’s Science #535750) ❏❏ Colored pencils Check Your Understanding 3.1 What is a whisk fern? Whisk ferns are members of phylum Psilotophyta. The small plant has no leaves or roots and a dichotomously branching green stem with small scales that bears bright yellow synangia on lateral branches. 3.2 What was Calamites? Calamites spp. were giant members of the horsetail family that grew to heights of more than 20m during the Carboniferous. 3.3 Describe several uses of horsetails. Through the centuries, horsetails have been used as food and medicine. Today, however, the consumption of horsetail is discouraged. Medically, ancient cultures used horsetail as diuretics; astringents; agents to discourage lice, fleas, and mites; and a cure for diarrhea. Many Oriental gardens feature horsetails. Pioneers used horsetails to scrub pots and sharpen knives. 3.4 Given the description of elaters provided on p. 327, describe their function. Elaters are winglike structures found on the spores of horsetails. They serve to increase the distribution of the spores. Chapter 21 | The Green Machine: Understanding the Seedless Vascular Plants 6 EXERCISE 21.4 Phylum Pterophyta Estimated Exercise 21.4 Completion Time: 1 hour Procedure 1 Macroanatomy of Ferns Estimated Procedure 1 Completion Time: 20 minutes Materials ❏❏ Dissecting microscope ❏❏ Living or preserved specimens of several species of ferns (local nursery, field, or other source) ❏❏ Scalpel ❏❏ Petri dishes ❏❏ Water ❏❏ Dropper ❏❏ Microscope slides and coverslips ❏❏ Acetone (Carolina Biological #841500) ❏❏ Rubbing alcohol ❏❏ Salt water ❏❏ Distilled water ❏❏ Gloves ❏❏ Colored pencils Answers to Procedural Questions 5 Remove another sorus from the pinnae with a scalpel, and place it in a petri dish. Place one drop of acetone on the sorus, and observe it with a dissecting microscope. What happened? The sorus immediately popped open and released the spores. 6 Repeat Steps 3–5, using rubbing alcohol, salt water, and distilled water. What happened? Running alcohol, salt water, and distilled water had no immediate effect on the sori. Procedure 2 Microanatomy of Ferns Estimated Procedure 2 Completion Time: 20 minutes Materials ❏❏ Compound microscope ❏❏ Prepared microscope slides: pinnae (Ward’s Science #914901) and sori (Carolina Biological #299500) of a maidenhair fern, a fern gametophyte, archegonia (Carolina Biological #299278) and antheridia (Carolina Biological #299248) of a gametophyte, a transverse section through a stem of a fern, and a transverse section through a sporocarp of Marsilea Chapter 21 | The Green Machine: Understanding the Seedless Vascular Plants 7 Procedure 3 Bringing Polypodium Ferns Back to Life Estimated Procedure 3 Completion Time: 20 minutes Materials ❏❏ Dry Polypodium sp. (Carolina Biological #156396) ❏❏ Water ❏❏ Paper towels ❏❏ Plastic container Answers to Procedural Questions 2 Make your observations. Answers will vary. Check Your Understanding 4.1 What is the function of sori? The spores are produced in sporangia that appear as distinct brown spots on the underside of the frond, called sori. 4.2 How does dried Polypodium sp. react to water? The Polypodium sp. begins to regain its green color and becomes pliable. 4.3 Sketch and label a fern frond. Sketches will vary, but make sure students
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