The Green Machine Understanding the Nonvascular 20

To the Instructor For many students, plants are not as exciting as animals. This is particularly true of the nonvascular plants. However, this group of plants has some interesting members and can be highlighted with some good examples and interesting facts. This chapter can easily be modified to teach along with other chapters on diversity. The instructor can pick and choose activities from these chapters to meet the needs of the students.

Topics for Discussion

77 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. 77 Discuss the classification and basic evolution of the nonvascular plants. 77 Discuss and bring in local specimens or photographs of the plants discussed in this chapter. 77 Compare and contrast nonvascular and vascular plants. 77 Discuss the phyla of the nonvascular plants included in this chapter, providing specific examples, natural history, uses, life history, and anatomical information. 77 Discuss the environmental, industrial, and medical importance of the nonvascular plants.

Total Estimated Completion Time: 1 hour, 30 minutes

1 Exercise 20.1 Phylum Hepatophyta Estimated Exercise 20.1 Completion Time: 30 minutes

Procedure 1 Macroanatomy of Marchantia

Estimated Procedure 1 Completion Time: 15 minutes

Materials ❏❏ Dissecting microscope ❏❏ Living specimen of Marchantia (Carolina Biological #156540) ❏❏ Colored pencils

Procedure 2 Microanatomy of Marchantia

Estimated Procedure 2 Completion Time: 15 minutes

Materials ❏❏ Compound microscope ❏❏ Prepared slide of Marchantia (Carolina Biological #298698) ❏❏ Colored pencils

Chapter 20 | The Green Machine: Understanding the Nonvascular Plants 2 Check Your Understanding

1.1 What is the function of a rhizoid? On the lower surface of Marchantia are hairlike structures called rhizoids. The rhizoids extend into the soil and anchor the thallus.

1.2 Describe asexual and sexual reproduction in Marchantia. Marchantia is capable of both asexual and sexual reproduction. Asexually, small cup-shaped structures called gemma cups (or splash cups) appear on the upper surface of the thallus and contain tiny pieces of tissue, gemmae. The gemmae detach (perhaps through the action of raindrops), establish a new location, and grow into a new plant. Sexually, like all plants, the life cycle of Marchantia has a and a generation. During the gametophyte generation, male and female sex cells are produced on separate umbrella-shaped structures that rise above the plant, called gametophores. The top portion of the male gametophore, the antheridiophore, is ­composed of antheridia containing numerous sperm cells. The female archegoniophore possesses archegonia, each containing a single egg. Raindrops or splashing water carry sperm to the awaiting egg. After fertilization occurs, the resulting zygote eventually develops into a sporophyte.The maturing sporophyte is anchored to the archegoniophore by a knob-like foot. A thin seta, or stalk, connects the foot to the main body, called the . Sporocytes within the capsule undergo meiotic division and produce haploid , or meiospores. Initially, the immature sporophyte is protected by a structure called the calyptra. The spores possess structures called elaters that aid their dispersal into new environments. The spores germinate, forming a new gametophyte.

1.3 Compare and contrast thallus and leafy liverworts. The thallus liverworts, which possess leaflike lobed bodies (thalli), are usually found living along creek banks or on moist soil. The leafy liverworts, the majority of liverworts, which at first glance resemble , are more commonly found in tropical environments.

Chapter 20 | The Green Machine: Understanding the Nonvascular Plants 3 Exercise 20.2 Phylum Anthocerophyta Estimated Exercise 20.2 Completion Time: 20 minutes

Procedure 1 Macroanatomy of Anthoceros

Estimated Procedure 1 Completion Time: 10 minutes

Materials ❏❏ Dissecting microscope ❏❏ Living specimen of Anthoceros if available (may have to be collected locally) ❏❏ Colored pencils

Procedure 2 Microanatomy of Anthoceros

Estimated Procedure 2 Completion Time: 10 minutes

Materials ❏❏ Compound microscope ❏❏ Prepared slides of Anthoceros (Carolina Biological #298680) ❏❏ Colored pencils

Check Your Understanding

2.1 What is the function of rhizoids in ? The rhizoids extend into the soil and anchor the thallus.

2.2 Where can one find hornworts? Most liverworts are terrestrial, living in moist environments, but several aquatic species have been described.

Chapter 20 | The Green Machine: Understanding the Nonvascular Plants 4 Exercise 20.3 Phylum Bryophyta Estimated Exercise 20.3 Completion Time: 40 minutes

Procedure 1 Macroanatomy of Polytrichum

Estimated Procedure 1 Completion Time: 10 minutes

Materials ❏❏ Dissecting microscope ❏❏ Living specimen of Polytrichum (Ward’s Science #864360) ❏❏ Colored pencils

Procedure 2 Microanatomy of Polytrichum

Estimated Procedure 2 Completion Time: 10 minutes

Materials ❏❏ Compound microscope ❏❏ Blank slides and coverslips ❏❏ Medicine dropper ❏❏ Leaflet or prepared slides ofPolytrichum (Ward’s Science #914341) ❏❏ Colored pencils

Chapter 20 | The Green Machine: Understanding the Nonvascular Plants 5 Procedure 3 Sphagnum and Water Absorption

Estimated Procedure 3 Completion Time: 20 minutes

Materials ❏❏ 5 grams of Sphagnum (purchase peat locally) ❏❏ 5 grams of a true sponge ❏❏ 5 grams of an artificial sponge (purchase locally) ❏❏ 5 grams of a paper towel ❏❏ Scale ❏❏ 4 beakers (250 ml) ❏❏ 100 ml graduated cylinder ❏❏ Wax pencil ❏❏ Stopwatch

Answers to Procedural Questions Write a hypothesis regarding this activity. Answer will vary.

4 Discuss your findings. The natural (animal) sponge is much more absorbent than the others.

Check Your Understanding

3.1 Describe two ways in which mosses can reproduce. Mosses are capable of asexual reproduction through fragmentation, but they undergo an alternation of generation with gametophyte and sporophyte stages. The “leafy” are either male, bearing antheridia, or female, bearing archegonia. Flagellated sperm cells exit the antheridia and travel, with the aid of water, to the archegonia, where a single egg is fertilized.

3.2 Why was Sphagnum successful as a bandage in World War I? In World War I, peat moss was used in making bandages. The peat moss was more absorbent than cotton, and the infection rate among the wounded also was reduced significantly because the pH of the peat moss was lower than cotton and inhibited bacterial growth.

3.3 Where can Polytrichum sp. be found? Polytrichum sp., haircap moss, is a common moss that can be found living in bogs.

Chapter 20 | The Green Machine: Understanding the Nonvascular Plants 6 Chapter 20 Review 1 What are 10 reasons you should “thank a plant”? x Source of food x Source of oxygen x Source of medicine x Shelter for animals x Used in making paper x Used for lumber x Source of shade x Prevents erosion x Source of raw materials, such as resin and turpentine x Aesthetic value

2 To conquer the land, what sort of adaptations did early land plants have to develop? Plants had to develop a protective integument, a system for conducting food and water, and new reproductive strategies.

3 Compare and contrast nonvascular plants with vascular plants. Nonvascular plants lack specialized conducting tissues to transport water and nutrients throughout the plant’s body. In addition, these plants lack true , stems, and . Examples of nonvascular plants are liverworts, stoneworts, and true mosses. Vascular plants can be divided into the seedless vascular plants and the plants. Vascular plants possess specialized tissues for conducting water and nutrients throughout the plant. In modern ­vascular plants, xylem conducts water and dissolved minerals, and phloem conducts nutrients, such as sucrose, ­hormones, and other molecules. The cells responsible for conducting water are often strengthened by the polymer lignin, which allows the plant to grow tall. In vascular plants, the sporophyte generation is dominant and possesses the vascular tissues. Vascular plants have a waxy cuticle for protection against desiccation as well as small openings called stomata on photosynthetic structures to allow for gas exchange. Vascular plants also possess true roots, stems, and leaves. The seedless vascular plants include the club mosses and the . The seed plants make up the largest group of vascular plants and include such examples as ginkgos, cycads, conifers, and zinnias.

4 Describe the process of alternation of generations. The life cycle of plants is characterized by alternation of generations. In this process, two distinct generations give rise to each other. The haploid (n) gametophyte generation is characterized by the production of male and female gametes through cell division. The male and female gametes fuse during fertilization, forming a diploid sporophyte. The sporophyte generation is diploid (2n). produce haploid spores that undergo cell division to form a gametophyte. In nonvascular plants the gametophyte generation is dominant, but in seedless vascular plants and seed plants, the sporophyte generation dominates.

5 Name several characteristics and give several examples of phylum Hepatophyta. Phylum Hepatophyta includes approximately 8,000 species of small nonvascular plants commonly known as ­liverworts. Two distinct types of liverworts have been described. One is the thallus liverworts, which possess leaflike lobed bodies (thalli), such as Marchantia spp., and are usually found living along creek banks or on moist soil. The leafy liverworts, the majority of liverworts, which at first glance resemble mosses, such asLepidozia spp., are more commonly found in tropical environments.

Chapter 20 | The Green Machine: Understanding the Nonvascular Plants 7 6 Name several characteristics and give several examples of phylum Anthocerophyta. The hornworts are a relatively obscure group of nonvascular plants belonging to phylum Anthocerophyta. Approxi- mately 100 species have been described to date. Hornworts usually live on moist ground in the shade. They are small, only 2 cm in diameter and up to 5 cm high, and easy to overlook. The thallus body has pores and cavities filled with mucilage. In many hornworts, nitrogen-fixing cyanobacteria live in the rich mucus. Rhizoids help anchor the minute plant. Asexually, many species reproduce through fragmentation. In hornworts, the sporophytes are ­distinct, looking rather like a green tentacle arising from a thin thallus gametophyte. The archegonia and antheridia are located in rows beneath the upper surface of the thallus gametophyte. The most studied is Anthoceros sp.

7 Name several characteristics and give several examples of phylum Bryophyta. True mosses have been placed in phylum Bryophyta. Presently, nearly 15,000 species of mosses have been identified. The gametophyte stage of mosses consists of small, spirally arranged leaflike structures surrounding a central axis. The blades of the leaflike structure are one cell layer thick, lack and stomata, and surround a thickened midrib. Rhizoids anchor mosses to their substrate. Mosses are capable of asexual reproduction through fragmentation, but they undergo an alternation of generation with gametocyte and sporocyte stages. Polytrichum is an example of a true moss.

8 Sketch and label Polytrichum Sketches will vary, but make sure students label nonvascular leaflike structures, nonvascular stem-like structures, rhizoids, mature male gametophyte, and mature female gametophyte.

Calyptra B Operculum C Capsule of Capsule of sporophyte sporophyte (covered by (with calyptra calyptra) absent)

Stalk (seta) Stalk (seta)

Gametophyte

Chapter 20 | The Green Machine: Understanding the Nonvascular Plants 8