lab #5 mosses & ferns. non-vascular & vascular seedless plants major division of plants into:...

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  • Slide 1
  • Lab #5 Mosses & Ferns
  • Slide 2
  • Non-Vascular & Vascular Seedless Plants major division of plants into: non-vascular & vascular non-vascular plants are known collectively as the bryophytes divided into: the mosses (Phylum Bryophyta) the liverworts (Phylum Hepatophyta) the hornworts (Phylum Anthocerophyta) vascular plants can be divided into: seedless and seed- bearing seedless plants are the lycophytes and the pterophytes Division Lycophyta club mosses Division Pterophyta ferns, horsetails and whisk fers the seed bearing plants are divided into: the gymnosperms non-flowering plants the angiosperms flowering plants
  • Slide 3
  • Plant Life Cycles alternation of generations: alternating between a multicellular haploid structure (gametophyte) and a multicellular diploid structure (sporophyte) alternating between a gametophyte stage and a sporophyte stage Mitosis ** as plants evolve there is an increasing importance of the sporophyte over the gametophyte
  • Slide 4
  • main steps: 1. haploid spore undergoes mitosis to produce the haploid gametophyte 2. gametophyte grows and produces male and female reproductive structures via mitosis antheridium & archegonium artheridium produces sperm, archegonium produces an egg egg fertilized by sperm to produce a diploid zygote 3. zygote undergoes mitosis to grow into a diploid sporophyte 4. sporophyte undergoes meiosis to produce haploid spores 5. back to step #1
  • Slide 5
  • Plant reproduction terms sporophyte (diploid) = spore producing plant that bears sporangia (singular = sporangium) sporangium = structure that produces haploid spores by meiosis spores (haploid) = released cells that will grow via mitosis to generate a gametophyte gametophyte (haploid) = multicellular structure that bears male and female gametangia (singular = gametangium) gametangium (haploid) = multicellular structure for the production of male and female gametes via mitosis archegonium (haploid) = female gametangium that produces an egg antheridium (haploid) = male gametangium that produces multiple sperm
  • Slide 6
  • Non-vascular plants (bryophytes) bryophytes = ancient group of non-vascular plants that share a common ancestor ancestor 475 million years old have not given rise to any other living group of plants but they still exist today!! lack the vascular tissues xylem & phloem gametophyte is still the dominant form of the life cycle what we identify as the plant Phylum Bryophyta Phylum Hepatophyta Phylum Anthocerophyta
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  • Phylum Bryophyta Mnium hornum Sphagnum peat moss
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  • Phylum Bryophyta mosses gametophyte stage of the life cycle thallus (heart-shaped) body bears male and female gametophores with gametangia gametophore leafy shoots of the moss gametophyte thallus anchored to the substrate via rhizoids root-like structures NOT true roots multiple cells that form up end to end to produce a filament non-photosynthetic do NOT absorb nutrients and water anchorage only
  • Slide 9
  • Non-vascular plants non-vascular mosses are not to be confused with the vascular club mosses = lycophytes some mosses are NOT mosses at all Irish moss (red seaweed), reindeer moss (lichen)
  • Slide 10
  • Bryophyte General Life Cycle: The Gametophyte dominant stage in all bryophytes release of spores onto favorable habitat the spore germinates into a threadlike protonema covers a large surface area for absorption or water and minerals protonema grows into a haploid gametophyte each protonema produces a bud with an apical meristem (stem-cell like tissue for growth) the AM develops into the gamete producing gametophyte the leafy shoots of the moss gametophyte are called gametophores the tips of the gametophore bear the male or female gametangia the gametophyte of mosses is the actual moss!!
  • Slide 11
  • Bryophyte General Life Cycle : The Gametophyte reproductive structures of the gametophyte = gametangia (singular = gametangium) multiple gametangia develop on each gametophyte some bryophytes are bisexual both antheridium and archegonium on the same gametophyte plant = monoecious e.g. liverwort bryophyte most moss bryophytes have separate antheridium and archegonium located on separate gametophytes on separate plants = dioecious male and female moss plants production of the gametes by mitosis since the gametophyte is haploid already!!!
  • Slide 12
  • Bryophyte General Life Cycle : The Sporophyte fertilization of the egg is followed by development of the embryo within the archegonium the embryo develops into a sporophyte (diploid) - remains attached to the gametophyte via a foot for absorption of nutrients moss
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  • The Sporophyte sporophyte stage dependent upon the bryophyte gametophyte food and water passed to it via transfer cells transfer cells found in between the sporophyte and the gametophyte in a placenta-like tissue
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  • Moss Sporophyte anatomical features: 1. seta stem-like structure organ connecting sporangium to the gametophyte 2. foot base of the seta 3. sporangium site of spore production opening = operculum 4. calyptra surrounds and protects the sporangium may be bald or hairy
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  • Polytrichum commune hairy cap moss SPOROPHYTE GAMETOPHYTE calyptra around the sporangium stem (seta) GAMETOPHYTE (leafy shoot)
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  • Bryophyte General Life Cycle : The Sporophyte haploid spores develop in the sporangium via meiosis since the sporangium is diploid the spores are dispersed and settle onto a new substrate from these spores comes new protonemata (singular = protonema) hornwort and moss sporophytes tend to be large and more complicated liverwort sporophytes are microscopic moss hornwort liverwort
  • Slide 17
  • Phylum Hepatophyta liverworts share some similarities with mosses but there are some distinct differences gametophyte and sporophyte form gametophyte can be found as either leafy or thalloid (depending on species) thallus has no stems or leaves thallus gametophyte can be 1 to 2 cells thick or multicellular with tissue differentiation rhizoids are unicellular (like mosses) elongated single cells often covered with scales role in anchorage only many thalloid forms have gemmae cups for asexual reproduction
  • Slide 18
  • Phylum Hepatophyta leafy gametophyte can look a lot like the gametophyte of mosses very small leaves (about 1cm long) - arranged as two rows along the sides of the stem rhizoid is very similar to the moss rhizoid leafy gametophyte thallus gametophyte
  • Slide 19
  • Marchantia Gametophyte Marchantia gametophyte is made up of broad shaped leaves = thallus growing out of the gametophyte are stalked structures - called gametophores palm-tree female & umbrella male since both of these are found on the same sporophyte plant = monoecious Archegonia and antheridia of Marchantia (a dieocious liverwort) Male gametophore Antheridium with sperm Female gametophore Archegonium with egg the gametophyte of the liverwort is the actual liverwort!! antheridium gametangium with sperm archegonium gametangium egg Male gametophore Female gametophore
  • Slide 20
  • Male Gametophyte female gametophore male antheridium male gametophore looks like a patio umbrella that grows up from the gametophyte/liverwort male gametangia (antheridia) found embedded in the top surface of the gametophore several antheridia clustered onto an antheridial head or receptacle
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  • Female Gametophyte female gametophore looks like a palm tree growing up from the gametophyte/liverwort female gametangia (archegonia) found dangling underneath archegonium = venter with an egg + tubular neck
  • Slide 22
  • The Liverwort Sporophyte in the liverwort the fertilized egg in the archegonium becomes the embryo the embryo develops into the diploid sporophyte sporophyte is attached to the female gametophore by a seta and a foot the sporophyte is small and dangles off the female gametophore like coconuts end is the sporangium contains haploid spores formed by meiosis
  • Slide 23
  • Sporophyte forms after the egg in the archegonium is fertilized comprised of a foot, seta and a dangling sporangium sporagngium is attached to the female gametophore by the foot and a seta spores are expelled out all at once (unlike mosses) presence of elaters with contract and expand with humidity to expel the spores once the spores are dispersed, the liverwort sporophyte withers away (unlike mosses) Female Gametophore with archegonia Marchantia polymorpha, a thalloid liverwort Foot Seta Sporangium 500 m Marchantia sporophyte (LM)
  • Slide 24
  • some uprisings are called gemmae cups contain asexual gemmae discs of green tissue that when dispersed generate new gametophytes develop by mitosis from the gametophyte Marchantia Asexual reproduction gemmae cups & cross section
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  • Phylum Anthocerophyta: Hornworts An Anthroceros hornwort species Sporophyte Gametophyte
  • Slide 26
  • The Economics of Moss mosses have very lightweight spores- easy distribution & the establishment of mosses around the globe very common and diverse in moist forests and wetlands can help retain nitrogenous compounds in the soil via their relationships with cyanobacteria many species


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