Nonvascular Plant

Lab Topic 16
Investigating Plant Phylogeny: Seedless Plants

Nonvascular Seedless Plants

How to study for the practical

Learn the language:
For this topic a vocabulary list is given in your lab manual. You need to know the definitions of the terms. Make flashcards for those that you do not know and work to learn the definitions.

Seek the big picture:
In lab manual a list of Key Concepts and Objectives are given. Be sure that you can explain how the lab addresses or illustrates each.
You will probably find it helpful to outline the background section at the beginning of each lab topic in the manual as it attempts to give you a “big picture” overview.

Apply your knowledge of terms and concepts to reality:
Review the images on this www site for each lab topic in the practical.

You need to develop visual memory so that you can recognize images similar to these in the lab practical questions.

As you look at the images, answer any questions that given with the image. Use you lab notebook and lab manual to check your answers.

Synthesize and consolidate you knowledge:
Draw life cycle diagrams where you can. For each organism, know when mitosis and meiosis occur in the life cycle. Be able to describe the ploidy levels as well as the names of different life cycle stages. If there are special organs involved in sexual or asexual reproduction, know the names, functions and what they look like.

Read and outline Background section of lab manual. Pay attention to Figure 16.2 and Table 16.1.

Anatomy and Life Cycle of Stonewort

Images of Nitella to come Review photos in Figure 16.3 in lab manual

What is this? A protist, or early seedless plant?
Please state the evolutionary significance of this organism.
Which of the following shows the close relationship between this organism and plants? A. Photosynthesis, B. Site of gamete production, C. Multicellular Body plan, D. Vascular system
Describe four features that are shared in common between plants and green algae.
Name one feature that supports this protist (green algae) as the ancestor to the land plants.
What are gametangia?

Phylum (=Division) Hepatophyta (Liverworts)--Representative genus Marchantia

Review life cycle diagram in Figure 16.5 in lab manual

Which of the following life cycle stages in Hepatophyta is dominant and what is its ploidy in that stage? A. Gametophyte, 1N; B. Gametophyte, 2N; C. Sporophyte, 1N; D. Sporophyte, 2N

What division does this organism belong to?

List two adaptations to the terrestrial environment that this plant shares with all other plants.

List two adaptations to the terrestrial environment that are found in ferns and flowering plants that are LACKING in this plant.


Thalli with gemmae cups	Gemmae cup at 100X (stained)
What is the function of gemmae cups? What is the difference between sexual and asexual reproduction?	Would you expect the cells in gemmae cups to divide by mitosis or meiosis? What is the function of this structure? What is the ploidy level of gemmae?


A single thallus	Cross section of thallus with rhizoids at 100X (stained)	Air pore on upper surface of thallus at 400X (stained)
Is this stage in the development of a liverwort a gametophyte or a sporophyte? Do the cells in this thallus divide by mitosis or meiosis as it grows? What is the ploidy level (haploid or diploid) of the photosynthetic tissues seen here?	What is the function of rhizoids? How many cells thick is a thallus?	What is the function of this pore? A thallus grows from a single cell. What is the name of that cell?


Antheridiophores	Longitudinal section of antheridiophore at 35X (stained)	Longitudinal section of several antheridia at 100X (stained)
If a liverwort has only antheridiophores, is it a male or female? Is this the gametophyte or a sporophyte stage of the life cycle?	What is the name of this structure? What is the function of this structure? What type of gamete is produced by this structure?	Do cells within the antheridia divide by mitosis or meiosis? Are antheridia gametangia?


Archegoniophores	Archegoniphores
Are archegoniophores male or female structures? Is this organism a gametophyte or a sporophyte?	What is produced inside the archegonia?


Longitudinal section of a stained archegoniophore at 35X (stained)	Longitudinal section of archegoniophore at 100X (stained)
What is the function of this structure? What type of gamete is produced by this structure?	What is the name of the structures hanging down from the undersurface of the cap? What are the dark structures in the chambers below the cap? What is their ploidy level?


Longitudinal section of archegonia at 400X showing eggs and neck canals (stained)	Sporophytes developing from fertilized eggs in archegonia at 400X (stained)
How are sperm transferred from the male to the female gametophyte? Describe how fertilization occurs in liverworts. Where does it occur? When fertilization occurs here, what develops? Are archegonia gametangia?	Is the sporophyte stage dependent on or independent of the gametophyte stage in liverworts? What does the sporophyte stage produce? What is the function of this structure?

Self quiz on life cycle stages

What is dominant generation in the life cycle of this plant?

Which one is the female and which the male gametophyte?

What is ploidy level of this structure?

Point to the thalli, gemmae cups, antheridiophores, and archegoniophores in the above photo.

General and Comparative Essay Questions

What event starts the sporophyte stage in the life cycle of a liverwort? Where does it occur?
What event starts the gametophyte stage in the life cycle of a liverwort? Where does it occur?
If you wanted to study meiosis in liverworts where would you look for cells that might be dividing by meiosis?
Write a short paragraph that explains alternation of generations in liverworts.
A count of the number of chromosomes in a cell from the thallus of a liverwort indicated it had 22 chromosomes. How many would you expect to find in a sperm of a liverwort? In a sporophyte? In a spore?

Phylum (=Division) Bryophyta (Mosses)

In the above photos, identify which are the gametophyte and sporophyte stages.
List two adaptations to the terrestrial environment that this plant shares with all other plants?
List two adaptations lacking in this plant that are found in other plants.
To what phylum does this organism belong?
Which of the stages of the plant's life cycle is dominant in this organism?
Does this plant have true vascular tissues?

Young Gametophyte Stages


Early protonema	Later protonema	Protonema with gametophyte bud (stained)
Is this the start of the sporophyte or the gametophyte stage of the life cycle? Are protonemal cells haploid or diploid? Protonema grow from what structure in the life cycle?	What is the ploidy level of this structure? What type of cell division would you expect to find in a growing protonema?	Are gametophyte cells haploid or diploid?

Mature Gametophyte Stages

What types of gametes are produced in this structure?
What is the function of the neck canal seen in central archegonium?
How does fertilization occur in mosses?
This structure produces gametes through the process of: A. meiosis; B. mitosis; C. diffusion.
Which of the following best describes the reproductive organ in the slide? A. Ovary, B. Microsporangia, C. Archegonia, D. Antheridia.
In this slide, would you expect to see eggs or spores and why?

Archegonia and paraphyses at 100X (stained)

Antheridium (stained) Longitudinal section of antheridium at 35X (stained) Moss sperm (small flagellated cells)

What type of cells are produced by the antheridium?
Are these cells produced by meiosis or mitosis?
In mosses, the sperms develop by (A) mitosis; (B) meiosis; (C) fertilization; (D) double fertilization. Point to an antheridium.
What is the ploidy level of cells in the antheridium?
What type of gamete is produced by this structure?
Which of the following best describes the reproductive organ in the slide? A. Ovary, B. Microsporangia, C. Archegonia, D. Antheridia
The cells stained red in this antheridia/archegonia slide were produced by ___________ (mitosis or meiosis). What is the ploidy level of sperm?
Describe the role of water in fertilization in the bryophytes.
What is the name and function of this structure?

Mature Sporophyte Stages

Sporophyte development from Gametophyte Immature and mature Capsule Sporophyte capsules

Is the sporophyte nutritionally dependent or independent of the gametophyte?
Can you grow a moss sporophyte alone in the soil? Why?
Is sporophyte tissue diploid or haploid? Why?
Are sporophyte cells produced by mitosis or meiosis?
What phase of the life cycle is indicated? Spore are produced inside these capsules by what type of nuclear division?

Capsules Capsule l.s. Capsule l.s. at 35X (stained)

What is the name of the "lid" on the capsule?
What is the function of the peristome?
What does this structure contain?

WHat is the ploidy level of the chamber wall tissues? Of the chambers contents?
What do capsules produce?
Why are these products important in the life cycle?
Are these products the result of meiosis or mitosis?
What is the ploidy level of this brown cells in the chambers?

Cross section of moss gametophyte stem (stained)
Do you see any evidence of vascular tissue in the cross section?

General and Comparative Questions

Describe the alternation of generations that occurs in the life cycle of a moss.

How do spores differ from seeds?

What adaptations do mosses have to a terrestrial way of life?

What event starts the sporophyte stage of the life cycle of mosses? Where does it occur?

What event starts the gametophyte stage of the life cycle of mosses? Where does it occur?

Which stage in the life cycle of a moss is haploid? Sporophyte? Gametophyte?

Describe the gametangia in mosses.

Explain why you would not expect to find only male moss gametophytes growing in one place in the wild and female gametophytes in another, quite far from the males.

A species of moss has a diploid number of chromosomes equal to 28. How many chromosomes will be found in an egg? Zygote? Spore? Photosynthetic "leaf?" Protonema?

If you were to examine mosses from around the world, none would be more than a foot tall (if that). How can you explain this? Is there some limitation built into the moss body plan?

Mosses tend to thrive in moist damp places and are rarely found in dry places in direct sunlight. How do you explain this?

Click here to go to Pterophyta (Ferns)

Click to go to Biology 201L Index page

Credits

Photos by Maria Oehler, Linda Westgate and Botanical Society of America
Layout and text by W. D. Dolphin


Antheridium (stained)	Longitudinal section of antheridium at 35X (stained)	Moss sperm (small flagellated cells)
What type of cells are produced by the antheridium? Are these cells produced by meiosis or mitosis? In mosses, the sperms develop by (A) mitosis; (B) meiosis; (C) fertilization; (D) double fertilization.	Point to an antheridium. What is the ploidy level of cells in the antheridium? What type of gamete is produced by this structure? Which of the following best describes the reproductive organ in the slide? A. Ovary, B. Microsporangia, C. Archegonia, D. Antheridia The cells stained red in this antheridia/archegonia slide were produced by ___________ (mitosis or meiosis).	What is the ploidy level of sperm? Describe the role of water in fertilization in the bryophytes. What is the name and function of this structure?


Sporophyte development from Gametophyte	Immature and mature Capsule	Sporophyte capsules
Is the sporophyte nutritionally dependent or independent of the gametophyte? Can you grow a moss sporophyte alone in the soil? Why? Is sporophyte tissue diploid or haploid? Why? Are sporophyte cells produced by mitosis or meiosis? What phase of the life cycle is indicated?		Spore are produced inside these capsules by what type of nuclear division?