Plant Kingdom: Seedless, Nonvascular Plants

How many cells thick is the leaflet of the Polytrichum moss gametophyte?

1-2 cells thick.

Describe the sexual reproduction cycle of mosses.

1. 1N sperms are released from the antheridia on male gametophytes and then swim to the archegonia to fertilize eggs. 2. This produces a 2N zygote which develops into a diploid sporophyte which will grow out of the archegonium and differentiates into a slender seta with a swollen capsule at its apex. 3. This diploid sporophyte will grown on the gametophyte and eventually produce spores by meiosis 4. Spores will germinate, giving rise to gametophytes. 5. Gametophytes initially grow along the ground. 6. Buds will produce leafy gametophytes.

Describe the in depth sexual reproduction of Marchantia.

1. The capsule contains 2N sporangium and spore mother cells. 2. These 2N spore mother cells then undergo meiosis to produce 1N spores. 3. These spores will produce independent male and female gametophytes. 4. The archegoniospore produces archegonia, each of which contains an egg. 5. The anteridiophore produces antheridia, each of which produces many sperm. 6. Sperm need water to swim to eggs. 7. Sperm gets into antheridium by water. 8. After fertilization, the sporophyte develops within the archegonium and produces a capsule with spores. 9. Young sporophyte made (2N, produced from fertilized egg).

Cross section of gemmae of liverworts.

2 is gemmae

What are the steps of the alternation of generation cycle?

2N Sporophyte forms sporangium which then undergo meiosis. Meiosis produces 1N spores which form 1N gametophytes. Gametophytes form gametes which then undergo syngamy to produce a 2N zygote.

What are gemmae, and how are they dispersed?

A gemma (plural gemmae) is a single cell, or a mass of cells, or a modified bud of tissue, that detaches from the parent and develops into a new individual. It is used for asexual reproduction.

What is a Marchantia?

A liverwort.

Define Dioecious.

A species that has seperate male and female plants. Gametes are produced in specialized sex organs on upright stalks.

In Marchantia, what is the function of rhizoids?

Anchoring the plant; possibly absorption

How do the positions of the archegonium and antheridium in liverworts relate to their reproductive function?

Antheridia need to disperse sperm and are upright with pores on top of the antheridial disk; archegonia are protected under the surface of the archegonial disk.

Sexual reproduction structures of mosses.

Archegonia or antheridia are bore either on tips of the erect gametophyte stalks or as lateral branches on the stalks. The apex of the stalk of the female plant appears as a cluster of leaves, with the archegonia buried inside.

In bryophytes, ____ are multicellular sex organs that produce eggs and _____ are multicellular sex organs that produce flagellated sperm.

Archegonia, antheridia.

Describe the sexual reproduction structures in liverworts. What do they consist of?

Archegoniophores- specialized stalks on female plans that bear archegonia; archegonium are flask shaped which consist of a neck and venter which contains the egg. Antheridiophores- specialized stalks on male plants that bear antheridia. Sperm form in the antheridia.

What is the adaptive significance of the seta of the sporophyte growing well above the mat of the gametophyte ?

Better dispersal of spores. Taller and so the wind can take spores away.

Can you think of any evolutionary implications of the similarity between moss protonema and a filamentous green alga?

Both have similar form and live in similar habitat, selective pressures for developing these structures may have been similar+++

List two main reasons why the bryophytes are dependent upon water and are therefore only found in moist habitats.

Bryophytes lack xylem and phloem (vascular tissue) therefore they must be close to water for absorption. Bryophyte sperm also need to swim to the egg so they need a water source.

What are some uses of bryophytes?

CO2 fixation, degradation of rocks into soil, stabilizing soil, reducing erosion, fuel, whiskey production, and as packing material

Describe the sporophyte of a moss.

Consists of capsules located atop stalks called setae, that extend upward from the moss gametophyte. The sporophyte dependent and attached on the gametophyte by the foot.

What does the antheridiophore on a Marchantia look like?

Contains male reproductive structure.

Is the capsule of mosses haploid or diploid?

Diploid because its is a part of the sporophyte of a moss.

Where is the egg located in the archegonium of mosses?

Egg is enlarged cell at base of neck

What is the functional significance of the response of liverwort elaters to moisture?

Elaters help disperse spores by twisting In humid conditions. They coil and in dry conditions expand and rupture, pushing out the spores

T or F: The sporophyte is the dominant phase of bryophytes.

False

Describe the body of liverworts.

Flattened from front to back and bilaterally symmetrical, meaning that if you cut its thallus down the middle, it would appear as a mirror image.

Are liverworts gametophyte or sporophyte dominant?

Gametophyte

Are mosses gametophyte or sporophyte dominant?

Gametophyte

Is the most obvious green part of a moss the sporophyte or the gametophytes?

Gametophyte

Are bryophytes sporophyte or gametophyte dominant?

Gametophyte dominant

Describe the gametophyte of a moss.

Gametophyte is leafy and stands upright.

What is the functions of pores in Marchantia?

Gas Exchange

What did land plants evolve from?

Green Algae

Are sperm haploid or diploid in moss gametophytes?

Haploid.

Anthoceros is the most familiar ______.

Hornwort

What does the phylum anthocerophyta include?

Hornworts

Describe the in depth asexual reproduction of Marchantia.

It can reproduce asexually by fragmentation. Gemma cups grow on the thallus and inside them, there are lens-shaped outgrowths which are splashed out of the cup by rain. If a gemma lands in an adequate environment, it can produce a new gametophyte plant.

Describe the basics of the lifecycle of Marchantia.

It is dioecious. It undergoes sexual reproduction; they need free water or insects for sperm to swim to eggs. It asexually reproduces by gemmae cups

What is included under the term bryophytes?

Liverworts, hornworts and mosses which are the most primitive of terrestrial plants.

How do Marchantia (liverworts) and mosses different with respect to their asexual reproduction?

Marchantia reproduce asexually with gemmae/splash cups and mosses asexually reproduce with fragmentation.

What process produces moss spores?

Meiosis

Where is the moss sporophyte found in relation to the gametophyte?

Moss sporophytes consist of capsules located atop stalks called setae which extend from the moss gametophyte. The sporophyte depends on the gametophyte; sporophyte grows atop the gametophyte.

Is the sporophyte more prominent in mosses or liverworts?

Mosses

What does the phylum bryophyta include?

Mosses

How do mosses asexually reproduce?

Mosses lack structures such as gamma for asexual reproduction. They asexually reproduce by fragmentation

What is meant by "nonvascular plants"?

Plants without xylem and phloem, bark, true roots. This means their growth is limited to areas near water and their height is limited.

Are stomata or pores visible on the leaf surface of the Polytrichum moss gametophyte?

Probably not

In addition to lacking vascular tissue, what else links bryophytes to water?

Reproduction (sperm swims to egg).

Bryophytes have root-like structures called _____.

Rhizoids.

What does the sporangium contain?

Spore mother cells.

How to form protonema on mosses?

Spores germinate and form a photosynthetic protonema.

What is the body of a bryophyte?

Thallus

How is the life cycle of bryophytes physically shown? What parts are included in these structures?

The gametophyte is the leafy part (includes leaves and thallus) and the sporophyte is the spore bearing part (including the capsule and seta).

How does the symmetry of a moss gametophyte compare with that of a liverwort gametophyte?

The moss gametophyte (see pic) is radially symmetrical and liverworts are bilaterally symmetrical.

What is the function of the foot in the sporophyte of Marchantia?

The non photosynthetic sporophyte is connected to the gametophyte by the foot. Nutrient transport from gametophyte to sporophyte

Describe the structural representation of the alternation of generation in bryophytes.

The sporophyte (2N) is attached to and dependent on the gametophyte for the entire life cycle.

How does the thallus of a hornwort differ from that of other organisms

The thallus is long and flattened.

What does the archegoniophore on a Marchantia look like?

The thing shaped like a palm tree is an upright female reproductive structure (archegoniophores).

Structure of Archegonium of liverworts

The venter is spoon shaped and the egg is inside the venter. The "handle of the spoon" is the neck.

Where are the archegonia in hornworts?

They are embedded in the thallus and are in contact with surrounding vegetation.

Describe the body of mosses.

They are erect and radially symmetrical (circular)

Are spores produced by meiosis of sporophytes of liverworts 1N or 2N?

They are haploid 1N

Characteristics of Mosses

They are more visible, more widely distributed, and more diverse than liverworts. Better than liverworts at withstanding desiccation.

Describe the body of hornworts.

They are similar to liverworts meaning that they are flattened from front to back and bilaterally symmetrical, meaning that if you cut its thallus down the middle, it would appear as a mirror image.

Are bryophytes large?

They are small and found all over the world. They may have stems and leaf-like structures. There are almost 24,000 species of bryophytes.

Characteristics of hornworts

They are the smallest group of bryophytes (about 100 species). They are shaped like a long, tapered horn that protrudes from the flattened thallus.

What is an elater?

They attach to the spores to help with dispersal. In plants that do not have seeds, they function in dispersing the spores to a new location.

Do bryophytes have roots?

They don't have true roots, rather they have root-like rhizoid structures which are used for anchoring.

Describe the appearance of bryophytes, including their symmetry.

They have a gametophyte dominant stage. Their thallus (body) is erect and radially symmetrical (circular) and they are flat from front to back and are bilaterally symmetrical (2 equal halves).

Why are bryophytes considered primitive? What are their habitat limitations?

They lack a vascular system therefore they most live in moist habitats and their photosynthetic tissue must be near their water absorbing tissues.

Do bryophytes have a vascular system?

They lack well developed vascular systems, limiting their distribution to moist habitats.

T or F: Bryophytes lack vascular tissues, and as a result they are relatively small and inconspicuous.

True

Are Marchantia dioecious?

Yes.

What does the phylum lycophyta include?

club mosses

What does the phylum pterophyta include?

ferns

What does the phylum hepaticophyta include?

liverworts

Antheridia of liverworts

the dark circles are the antheridia

Is there a midrib vein in the Polytrichum moss gametophyte?

yes