Chapter 16 Bryophytes

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Chapter 16Bryophytes
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Outline

• Intro
• Comparative structure and reproduction
• P. Hepatophyta
• P. Anthocerophyta
• P. Bryophyta

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Taxonomic Grouping

• Non-vascular
• transitional btwn green algae and vascular plants

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Intro

• Liverworts/hornworts/mosses
• leafy, mostly moist locations, also
  tundra/deserts/aquatic
• Move to land
• lack vascular tissue X and P
• ? lignification
• avoid dessication via other tissues
• dominant gametophyte
• still have swimming sperm

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Intro

• Terms
• sporophyte diploid, produces spores
• gametophyte haploid, produces
  gametes
• gametangia structure where
  gametes form
• antheridia ? gametangia,
  produces sperm
• archegonia ? gametangia,
  produces eggs
• Alteration of generations

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Comparative Structure and Reproduction of
Bryophytes

• Jennifers Talk

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Phylum Hepatophyta Liverworts

• 6000 sp., inconspicuous but large mass
• Shaded rocks, soil, trees
• Develop from spores or
  protonema-like filament of cells
• 2 clades of liverworts
• complex thalloid liverworts -
  differentiated internal
  tissues
• leafy and simple thalloid liverworts -
  undifferentiated

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Thalloid Liverworts

• Moist, shady areas
• Differentiated thallus
• thallus body w/ undifferentiated root, stem,
  lvs
• dorsal side - chlorophyll-rich, bumps w/
  pores/air chamber
• ventral side - chlorophyll-less, rhizoids, scales
• Asexual reproduction via fragmentation
• Sexual reproduction via production of gemmae
  (vegetative tissue) in gemma cups on dorsal
  surface of gametophyte

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Thalloid Liverworts Riccia, Ricciocarpus

• Dichotomously branched gametophyte w/ embedded
  sporophyte
• Spores dispersed after sporophyte decays
• Ricciocarpus aquatic/terrestrial,
  bisexual (hermaphrodite)
• Riccia aquatic/terrestrial,
  unisexual/bisexual
  gametophytes

Riccia
sporophyte
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Thalloid Liverworts Marchantia

• Moist soil, rocks
• Dichotomously branched gametophyte
  w/ gametangia on gametophores
• gametophore fertile stalk w/ gametangia
• gametangia where gametes are formed
• Unisexual w/ distinctive gametophores
• antheridia borne on antheridiophores (?)
• archegonia borne on archegoniophores (?)

antheridia
archegonia
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Thalloid Liverworts Marchantia

• Sporophyte foot, seta, capsule
• Sporangium spores elaters
• sporangium where spores are made
• elater dehisce and twist to propel spores

spore
elater
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Leafy Liverworts

• Very diverse, grow on lvs and bark w/ high
  humidity
• Highly branched, forms small mats
• similar to moss except lvs flattened, lack
  midribs
• Perianth w/ archegonium
• Anthredia borne on androecium

sporophyte
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Phylum Anthocerophyta Hornworts

• 100 sp., 6 genera, similar looking to liverworts
• Gametophyte rosettelike, unisexual/bisexual
• symbiotic relationship btwn Anthoceros (hornwort)
  and Nostoc (cyanobacteria), N fixation
• Sporophyte foot, elongated capsule/
  sporangium, stomata
• spores dispersed when sporangium dehisces

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Phylum Bryophyta Mosses

• 9500 sp.
• 3 classes Sphagnidae (peat moss), Andreaeidae
  (granite moss), Bryidae (true moss)
• Not mosses reindeer moss, club moss, Spanish
  moss
• epiphytes grow on other plants,
  not rooted in soil

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Class Sphagnidae Peat Moss

• 1 living genus Sphagnum, 150 sp., diverged early
• Wet areas (i.e., bogs), dense clumps
• Commercial value

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Class Sphagnidae Peat Moss

• Sexual reproduction w/ antheridia and archegonia
  on ends of gametophyte, in winter, spores
  released 4 mo. later
• Sporophytes red/black capsules on
  pseudopodium, operculum (lid),
  
  spores released via explosion
• Asexual repro. via fragmentation

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Class Sphagnidae Peat Moss

• Distinctive characteristics
• protonema (young gametophyte) is platelike,
  1 cell thick and w/
  marginal meristem
• gametophyte stems bear 5 branches/node
• thus moplike
• lvs 1 cell thick w/ living cells surrounding
  large dead patches
• perforated stems and dead leaf cells
  high water holding
  capacity, 20x dry wt
• used as diaper absorbant, wound dressing
• decay resistant, lowers pH
• explosive operculum
• Used as fuel, potting media
• Peatlands 1 Earth surface
• stores 400 B metric tons C

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Class Andreaeidae Granite Moss

• 2 genera
• Blackish-green/dark reddish-brown
• Lives on granite or calcareous rocks in mtns or
  artic
• Slits in capsule spore discharge

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Class Bryidae True Moss

• Greatest diversity, true mosses
• Have rhizoids
• Unisexual/bisexual
• Fertilized w/ water, wind, insects
• Sporophyte on top of gametophyte
• Sporangia mature 6-18 mo.
• Also capable of fragmentation
• Rudimentary vascular system
• Stomata

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Class Bryidae True Moss

• Cushiony moss erect
  gametophyte w/ little
  branching,
  terminal sporophyte
• Feathery moss creeping
  gametophyte w/ lots branches,
  lateral
  sporophyte

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Moss lifecycle ? and ? gametangia dependent
sporophyte spore dispersal
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Archegonia in archegonial head
Anthredia in anthredial head
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Class Bryidae Spore Dispersal

• Peristome cap of sporangium (capsule)
• rings of teeth uncurl when dry to release spores
  in dry conditions
• unique to Bryidae

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Class Bryidae Vascular System

• Stems w/ central strand of water
  conducting tissue hadrom
• Hydroids water-conducting cells
• similar to tracheary elements in vascular
  plants, dead at
  maturity, lack lignin in wall
• Food-conducting tissue leptom
• Leptoids food-conducting cells
  surrounding hydroids
• similar to sieve elements in vascular plants,
  living at maturing
• Similar to protracheophytes/tracheophytes

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