Lab Practical 4: Survey of the Plant Kingdom

moss antheridium

-antheridium is blue -sperm is scaly inside

moss archegonium

-archegonium is red -egg is in center

moss sporophyte

-consist of capsules located atop stalks (setae) that extend upward from the moss gametophyte -calyptra covers apex of capsule, falls off when capsule matures, haploid spores formed by meiosis are inside capsule -operculum on tip of capsule that has hairlike teeth lining opening to control release of spores -a sporophyte is attached to the gametophyte by foot

sexual reproduction in liverworts

-dioecious (have separate male and female plants) -gametes from each plant are produced in specialized sex organs born on upright stalks -archegoniophores are specialized stalks on female plants that bear archegonia, consists of neck and venter which contains egg -antheridiophores are specialized stalks on male plants that bear antheridia, flagellated sperm are released and washed from antheridia during wet conditions and fertilize egg located in venter -zygote remains in venter and grows into sporophyte plant

sexual reproduction in mosses

-dioecious (male and female reproductive structures on separate individuals) -archegonia or antheridia are born either on tips of erect gametophyte stalks or as lateral branches on the stalks -apex of stalks of female plant appears as clusters of leaves with archegonia buried inside

Marchantia life cycle

-during sexual reproduction spores produced in capsule of sporangium germinate to form independent male and female gametophytes -archegoniophore produces archegonia which each contain an egg, antheridiophore produces antheridia which produces sperm -after fertilization sporophyte develops within archegonium and produces capsule with spores via meiosis -reproduces asexually by fragmentation and gemmae

plants

-evolved from freshwater green algal species more than 550 million years ago -autotrophic, contain chlorophyll a, have cell walls containing cellulose -alternation of generations

asexual reproduction in liverworts

-fragmentation, older center portions of thallus die leaving growing tips isolated to form individual plants -gemmae cups occur on dorsal (upper) surface of some thalli near midrib -gemmae inside gemmae cups splash out of cup by falling drops of rain -can produce new gametophyte plant in adequate environment

bryophyte life cycle

-gametophyte is dominant phase -antheridia swim to archegonia to fertilize egg -fertilized egg is zygote -zygote divides and matures in archegonium to produce haploid spores via meiosis -haploid spores develop into gametophyte

Phylum Bryophyta: mosses

-gametophyte plants are leafy and stand upright, withstand desiccation better than liverworts -grow in greater diversity of habitats than liverworts -gametophyte is radially symmetrical and is most conspicuous phase of moss life cycle

plant life cycle

-haploid gametophytes alternate with diploid sporophytes -gametophytes produce antheridia and archegonia from mitosis -sperm and eggs fuse during fertilization to produce first diploid cell of sporophyte (zygote) -meiosis occurs within sporangia (the spore producing organs of sporophyte) -resulting spores are haploid and first cells of gametophyte generation

moss life cycle

-haploid sperm are released from antheridia on male gametophytes -sperm swim through water to archegonia and down their necks to fertilize eggs -resulting diploid zygote develops into diploid sporophyte via mitosis -sporophyte grows out of archegonium and differentiates into a slender seta with a swollen capsule -capsule is covered with a cap formed from archegonium -sporophyte grows on gametophyte and produces spores by meiosis -spores germinate giving rise to gametophytes via mitosis

Compare and contrast the complexity of bryophytes and algae regarding their morphology, habitat, asexual reproduction, and sexual reproduction.

-morphology: bryophytes have leafy plant body; algae plant body varies from unicellular to multicellular or filamentous -habitat: bryophytes can live in aquatic and terrestrial; algae are usually aquatic -asexual reproduction: bryophytes fragmentation; algae cell division or binary fission -sexual reproduction: bryophytes alternation of generations: algae isogamy (two identical gametes), anisogamy (two dissimilar gametes), oogamy (male motile female immotile)

Phylum Anthocerotophyta: hornworts

-smallest group of bryophytes -sporophyte shaped like a long tapered horn that protrudes from flattened thallus -archegonia are not discrete organs, embedded in the thallus and are in contact with surrounding vegetative cells (growing not producing spores)

sporophyte of liverwort

-sporophyte is connected to gametophyte by foot -spores are produced by meiosis in capsule located on seta that extends downward from foot

archegonium of Marchantia

1) archegonium 2) neck 3) venter 4) egg

marchantia rhizoids

1) nonphotosynthetic tissue 2) rhizoids 3) pores 4) photosynthetic tissue

Why do you think that bryophytes are sometimes referred to as the amphibians of the plant kingdom?

Amphibians are those organisms which live on both land and in water. Bryophytes are called amphibians of the plant kingdom because these plants though live in soil but they need water for sexual reproduction.

How do the positions of the archegonium and antheridium 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.

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

Because of selective pressure on the organisms, it causes them to be similar in structure, adaptation, and environments

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

Better dispersal

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

Elaters coil in response to moisture. Elaters help disperse spores by twisting, expand when dry to push spores apart rupture spore case to release spores

Phylum Ginkgophyta

Ginkgo

Why is Sphagnum often used in shipping items that must be kept moist?

It absorbs any extra water that is around

How did liverworts get their name?

Liverworts get their name from their shape. Like moss, liverworts grow in moist habitats. They also don't have leaves, stems, or roots. Like moss, they use rhizoids to anchor themselves to the ground, rocks or trees.

In what ways are mosses morphologically similar to liverworts? In what ways are they different?

Liverworts have thorny leaves that do not have ribs. Liverworts can be either thallose or leafy. Thallose liverworts have large and rubbery leaves with flower-like capsules that contain spores for reproduction. Leafy liverworts have smaller leaves that are arranged on a small stem. Mosses look velvety. The stems of mosses are minute and contain simple leaves.

What ecological roles do liverworts, mosses, and hornworts play in their environment?

Liverworts, mosses, and hornworts are all decomposers that help break down dead organic matter (nitrogen fixation, soil stabilization). The also act as shelter for many small organisms. They release nutrients for many other plants or animals.

How does this compare with the paper towel?

Moss absorbs better

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

Mosses are radially symmetrical and liverworts are bilaterally symmetrical.

Are pores visible on the leaf surface?

Probably not

What features distinguish a moss from a liverwort?

The gametophyte is not differentiated into root, stem or leaves. Liverworts are thallose or foliose plants whereas mosses are foliose plants. The main difference between liverworts and mosses is the morphology of the gametophyte in each plant

What event begins the gametophyte phase of the life cycle? Where does this event occur in liverworts and mosses?

The life cycle begins as a haploid spore that germinates via mitosis. Both sperm and egg are produced on separate parts. This allows the sperm to swim down to the egg

What is the function of the foot?

absorbs nutrients and water from gametophyte archegonia

Where is the egg located in the archegonium?

center

Phylum Lycophyta

club mosses

Phylum Coniferophyta

conifers

Phylum Cycadophyta

cycads

Phylum Hepaticophyta: liverworts Marchantia (female)

earliest land plants

Phylum Pterophyta

ferns

Phylum Anthophyta

flowering plants

protonema

forms when moss spores germinate -resembles a branching filamentous alga -small threadlike filaments that then sprout one or more gamete forming gametophores

asexual reproduction in mosses

fragmentation

What event begins the sporophyte phase of the life cycle? Where does this event occur in liverworts and mosses?

fusion of egg and sperm into zygote develops into sporophyte, occurs in female gametophyte

What is the function of these pores in the thallus?

gas exchange

Phylum Gnetophyta

gnetophytes

Are sperm haploid or diploid?

haploid

Are the spores haploid or diploid?

haploid

Is the capsule haploid or diploid?

haploid

Phylum Anthocerotophyta

hornworts

bryophytes

include liverworts, mosses, and hornworts -most primitive group of terrestrial plants -green, rootlike structures called rhizoids, may have stem and leaflike parts -don't have specialized vascular tissues which transport materials between roots and shoots -moist habitats, relatively small and inconspicuous -fix CO2, degrade rocks to soil, stabilize soil, reduce erosion -used as fuel, production of Scotch whiskey, and as packing materials -plant body called thallus (hornwort and liverworts are flat while moss are circular)

What limits the height of mosses?

lack of vascular tissues

Phylum Hepaticophyta

liverworts

How many times its own weight did the moss absorb water?

many times

What process produces spores?

meiosis

Is the sporophyte of gametophyte more prominent in mosses or liverworts?

mosses

Phylum Bryophyta

mosses

Is the sporophyte of mosses ever independent of the gametophyte? Explain.

no, dependent on gametophyte because typically remains attached to it

How many cells thick is the leaflet?

one or two

structure of a moss

operculum is top of capsule

What are the functions of rhizoids?

serve the function of roots by anchoring the plants to substratum and absorption of water

Is there midrib vein?

yes