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Lab 10:NONVASCULAR PLANTS: (Bryophytes)

Lab 10:NONVASCULAR PLANTS: (Bryophytes)

Lab 10: Bryophytes 1 Name: ______Date/Lab time: ______

Lab 10:NONVASCULAR : (Bryophytes)

Supplies: with “sexual” organs Compound microscope Prepared slides showing moss archegonia Dissection scope and antheridia Slides and coverslips Prepared slides showing liverwort archegonia Liverwort with sexual organs and antheridia?? Slide of liverwort

Vocabulary to know: Alternation of generations, Antheridia, Archegonia , Diploid, Gametangia , Gametes , , Gemmae cup, Haploid, , , , Sporophyte, Terrestrial, Vascular

LAB SYNOPSIS: We will compare and contrast the available non-vascular plants in lab We will examine the morphology and anatomy of the vegetative and reproductive organs of the non- vascular plants.

Bryophytes - Non-vascular plants.

There are 4 phyla of plants that fit the above definition of bryophytes:

Kingdom Plantae Bryophyta () Phylum Hepaticophyta (liverworts) Phylum Anthocerophyta ()

Introduction: The Plantae is within the Eukarya. We will be looking at the nonvascular plants, commonly called the bryophytes during this lab. Tracheary elements are water conductive cells, which these plants lack. Nonvascular plants also lack nutritive conductive cells of the phloem. All land plants (the non-vascular plants and the vascular plants) probably evolved from aquatic green over 425 million years ago. In contrast to most algae, the liverworts and mosses have become adapted to a terrestrial existence. Members of these groups are green and have rhizoids ( hair like structures). Members are found in a wide range of habitats including Arctic and desert environments but, since they lack true , growth is restricted to times when surface moisture is available. During dry conditions, the body desiccates (dries) until water again becomes available. Non-vascular plants also require water for successful sexual . The are mobile and need water to swim to the egg. The body may be flattened (liverworts), or it may be erect and radially symmetrical (mosses). The reproductive organs, in contrast to those of the algae, are multicellular. As with the algae, the members of this group reproduce both sexually and asexual. In contrast to the algae (Kingdom Protista), all non-vascular plants are within the Kingdom Planta and thus have a well-established alternation of generation , consisting of an independent multicellular gametophyte (haploid )(1n) phase and a mostly dependent multicellular sporophyte (diploid )(2n) phase. Gametes (1n) (sperm and egg) are produced in 2 separate gametangia that are multicellular, the archegonia (female) and the antheridia (male). Lab 10: Bryophytes 2

In addition to alternation of generation, all plants share the following characteristics Plantae characteristics 1. Are multicellular photosynthetic 2. Plant are protected by tissues of the parent plant 3. - 4. a and b 5. as carbohydrate storage

*Recall that diploid (2n) refers to a cell that has pairs of homologous (2 sets). Like you, one set of chromosomes come from your mother the other set comes from your father. is a type of cell that separates the two sets of chromosomes. In humans this happens in the testicles (males) and the ovaries (females). During meiosis homologous pairs of chromosomes are separated resulting in cells containing a single set of chromosomes. These cells are haploid (1n). These would be like your sperm or egg. In the alternation of generations in plants, the product of meiosis is a haploid cell (). This 1n cell undergoes cell divisions producing a multicellular haploid organism (gametophyte). This gametophyte (1n) will produce 1n gametes (either sperm or egg). (We do not do this. We humans do not have a multicellular haploid phase). The 1n plant’s 1n sperm is released and ultimately swims to and fertilizes an (1n) producing a 2n zygote. The zygote undergoes mitotic cell division resulting in a multicellular diploid organism (sporophyte). It is this 2n sporophyte that will produce the new 1n spore, via meiosis, thus continuing the life cycle.

Classification of Currently Living Plants Phyla PHYLUM COMMON NAME CHARACTERISTICS Non-vascular plants Hepaticophyta Liverworts No filamentous stage; gametophyte flat

Anthocerophyta Hornworts Embedded archegonia; sporophyte grows basally

Bryophyta Mosses Filamentous stage; sporophyte grows apically (from the tip)

Non- Vascular plants Psilotophyta Whisk No true ; absent Lycophyta Club mosses Simple leaves in spirals; sporangia in axils Equisetophyta Horsetails Simple leaves in whorls; stems jointed Polypodiophyta Ferns Complex leaves; sporangia on underside of leaves

Seed plants () Cycadophyta Compound leaves; swimming sperm; on modified leaves Ginkgophyta Ginkgo Deciduous; fan-shaped leaves; swimming sperm Gnetophytes Vessels in vascular tissue; opposite, simple leaves Pinophyta Seeds in cones; needlelike or scale-like leaves

Flowering Seed plants (Angiosperms) Magnoliophyta Flowering plants ; carpels; much reduced ; seeds in

Lab 10: Bryophytes 3 PHYLUM BRYOPHYTA - MOSSES

Mosses differ from the liverworts in that the gametophyte (1n) of the moss begins as a filamentous, branching structure (protonema) and the mature gametophytic plant body is differentiated into “stem- like” and “leaf-like” parts. In addition, the sporangium ( ), contains a highly complex series of tooth-like structures that facilitate the dispersal of its . (see figure below) circle parts identified as you precede through the lab.

The above figure illustrates the alternation of generation in moss.

A. The Moss Gametophyte (1n)- Gamete Producing Generation of Moss

When you are looking at moss, you are seeing a multicellular haploid organism. Recall: in the seed plants this part of the life cycle (gametophyte) is microscopic. The main body of all other groups of plants is the sporophyte.

PROCEDURE- Observation and drawing 1. Examine fresh samples or prepared slides of an early moss gametophyte (1n) (protonema). Note its similarity to filamentous algae. Look for small -like structures along the length of the filament. These will mature into "leafy" gametophytes (1n).

2. Using a dissection microscope, examine the "leafy" part of the moss. This haploid gametophyte is the long-lived photosynthetic generation in the moss life cycle. The mature gametophyte consists of whorls of "leaves", a stem, and rhizoids. Although mosses and other non-vascular plants have true stems (note the nodes and internodes), they lack true leaves and true roots. Water and nutrients are taken in by rhizoids. Rhizoids are simple root-hair-like extensions from the . Lab 10: Bryophytes 4 3. Moss lacks true leaves. True leaves protect the apical during early growth. Moss “leaves” do not form in this way. Record your observation in your Plant Forms Table, noting that this is the gametophyte generation!

4. Using the dissection microscope examine the upper side of a "leaf" for the presence of a waxy cuticle that protects the plant from excess water loss.

Sketch the gametophyte (1n) generation of the moss. Label the “leaves”, stems and rhizoids.

5. Using a dissecting microscope, try to locate gametangia “gamete sacks” at the very tip of the "leafy" gametophyte (1n). This is where antheridia (male gametangia) or archegonia (female gametangia) are located. Sperm production: Many cells in the antheridia undergo cell divisions to produce the male gametes (sperm). Egg production: Only a single cell in the archegonia develops into the female gametes (egg). (No meiosis is required in these gametangia- remember the cells are already haploid).

6. Examine prepared slides of moss antheridia and archegonia and locate the sperm and the egg. Note the differences in appearances (good test question:).

Sketch moss gametangia (label location of sperm and egg) Antheridia Archegonia

Fertilization : One egg within the archegonia will be fertilized by one sperm resulting in the diploid zygote. The zygote will undergo cell division producing the diploid sporophyte generation (note this in the life cycle figure).

Lab 10: Bryophytes 5 B. The Sporophyte (2n) Spore Producing Generation of Moss

PROCEDURE- Drawings and descriptions (refer to life cycle figure)

1. Examine the available specimens of common mosses that consist of both the gametophytic and sporophytic generations. The diploid sporophyte is easily distinguishable since it sticks up out of the gametophyte and consists of a terminal sporangium (capsule) (often covered by a pointed cap termed the “ ”). A slender leafless stalk () and a foot that is embedded in the tissue of the "leafy" gametophyte. The relatively large (up to ~5cm) leafy gametophyte is photosynthetic and supports the nutrition of the sporophyte, which only lives a short time.

2. Use a dissection microscope; Draw and label the sporophyte (2n) generation of moss available in lab. Label the calyptra and capsule. Note the calyptra often falls off the mature sporophyte.

3. Under a dissection microscope, carefully separate the moss sporophyte (2n) from the gametophyte (1n). Note that the capsule often has a covering (the calyptra). Remove the calyptra (the calyptra is actually part of the gametophyte’s archegonia that gets ripped off as the sporophyte grows). Remove the calyptra, if present. The capsule had a lid (the operculum). Gently remove the operculum and examine the exposed surface of the capsule. Note the peristome teeth. As the capsule dries these teeth flick out the spores. Inside the capsule is where meiosis produces haploid spores.

4. Examine the prepared slide of a developing ovulate mature moss. Describe and draw what you see within the capsule.

5. Crush the capsule in a drop of water on a microscope slide and examine under the microscope. If the diploid sporophyte is mature, numerous spores will be present. These spores each contain a single haploid cell. Following haploid spore release from the capsule, and provided that suitable environmental conditions exist, the spore soon germinates and grow into a new gametophyte (1n).

The above represents in mosses. Asexual reproduction is primarily via fragmentation i.e. little pieces of the moss gametophyte break off and grow into a new plant (the moss in your yard is probably a clone of the same plant you spread around every time you mow). Fragmentation is especially common during the summer when the moss is desiccated (dry and dormant). Lab 10: Bryophytes 6 PHYLUM HEPATICOPHYTA - LIVERWORTS

Liverworts are so named because their plant body, called a , is flattened and lobed (like a liver). Early herbalists believed that these plants were beneficial in the treatment of liver disorders (beans were good for the kidney because they are kidney shaped; clover was good for the heart because leaflets are heart shaped etc.). Like the mosses, the dominant part of the life cycle of liverworts is the gametophyte (1n) generation. The sporophyte (2n) generation is even smaller than in the mosses. Although less common than mosses, liverworts can be found along streams on moist areas here in the Pacific Northwest.

A. The Gametophyte (1n) Generation Of Liverworts

PROCEDURE- observations and label drawing

1. Examine available examples of liverworts, noting the flattened gametophyte (1n) and rhizoids.

2. Look for gemmae cups on the thallus (leaf-like) surface which contain flat disks of green tissue called gemma. The gemma are a means of asexual reproduction in liverworts. Gemma are washed out of the gemmae cups when it rains and grow into new genetically identical liverworts.

3. Look for the stalked umbrella-like structures sticking up. Unlike in the mosses, the structures sticking out of the gametophyte generation are not the sporophyte. These umbrella shaped structures are specialized parts of the gametophyte. Two types are formed, one that will form antheridia (sperm sacs), the other will form the archegonia (egg sacs).

4. Examine the underside of a "leaf" and locate stomata. Stomata are holes into the plant that allow for gas exchange.

B. The Sporophyte (2n) Generation Of Liverworts

5. Unlike the relatively large moss sporophyte, the sporophyte in liverworts is microscopic and retained on the female umbrella-like sporangium. Look for (2n) in the prepared slides available, your textbook or online.

6. Label the liverwort figure with the following (gametophyte (1n), the sporophyte (2n) gemmae cups) Note the location of the male and female gametes (i.e. sperm and egg) on the umbrella-like structures and (label the antheridia and the archegonia).

7. Examine prepared slides of liverwort antheridia and archegonia and locate the sperm and the egg. Note the differences in appearances

Lab 10: Bryophytes 7 Questions

1. Compare and contrast the sporophytes of mosses and liverworts.

2. What is the function of the rhizoids present in non-vascular plants?

3. What adaptations do non-vascular plants have for their particular habitats? i.e. How do they survive outside the water?

4. What is a protonema? How would you tell a protonema from ? (see green algae figures online vs. a protonema)

5. You have now finished a survey of the Kingdom Plantae. What are some major trends in the evolution of land plants? Review your Plant Forms Table: (How does alternation of generation compare for each group? How do the appearances of true organs stems, leaves and roots relate? Etc.)

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