Bryophytes

The  Bryophytes

Similarities  to  green  algaeContains  chlorophyll  A  and  B  and  stores  starchCell  walls  made  of  cellulose,  hemicelluloses,  and  pectic substancesNon-­‐motile  egg  retained  after  fertilization

Some  have  zygote  coverings  resembling  integumentsAsymmetrically  flagellated  sperm  with  flagella  extending  from  the  side  rather  than  endAlso  begin  to  see  prominent  male  and  female  gamete  separation*Presence  of  sporopollenin

Bryophytes

Distinguishing  characteristicsPresence  of  male  and  female  gametangia in  a  layer  called  a  sterile  jacket

Antheridia  and  archegoniaRetention  of  zygote  and  developing  multicellularembryo  (sporophyte)  within  archegoniaPresence  of  multicellular diploid  sporophyte

Represents  permanent  shift  to  sporic meiosisSpores  **  containing  sporopollenin

Charophytes had  embryos  w/  sporopollenincharophytes (green  algae)  have  spores  w/??

Tissues  produced  by  an  apical  meristem

Sporic Meiosis

This  is  fine  when  fertilization  via  flagellated  sperm  is  easy  (aqueous  env)

Fertilizations  only  can  make  

Q:  What  about  terrestrial  environments  where  fertilization  by  flagellated  sperm  is  tough???

Sporic Meiosis

This  is  fine  when  fertilization  via  flagellated  sperm  is  easy  (aqueous  env)

Fertilizations  only  can  make  

Q:  What  about  terrestrial  environments  where  fertilization  by  flagellated  sperm  is  tough???

A:  Mitosis  of  zygote  once  =  8  haploid  cells  (6  times  =256)

Bryophytes

Still  retain  gametophyte  as  dominant  and  nutritionally  independent  stage

Sporophytes contain  only  single  sporangia  (compare  to  a  pine  tree)

Lack  true  specialized  vascular  tissue

Undifferentiated  spores!!

Liverworts

Phylum  Hepatophyta

Two  major  groupingsThallus

Leafy

Marchantia

Most  well  known  thalloidliverwortContains  antheriophoresand  archegoniophores

Modified  1n  tissue  containing  a  sporophytewhich  consists  of  a  foot,  seta,  and  capsuleNo  direct  connection  between  1n  and  2n

Oogonium of  Chara a  green  algae  (will  only  contain  a  single  2n  embryo)

Embryo  undergoing  mitosis  in  

similar  to  oogonium of  Chara

Marchantia

Antheridia Archegonia

Note:  these  are  not  the  

Hornworts

Phylum  Hepatophyta

Small  phyla  ~100  species

Unisexual  or  bisexual  gametophytes

Sporophytes are  often  

gametophyte

Hornworts

Sporophytes green,  w/  stomata,  and  photosynthetic

First  evidence  of  independence  in  sporophyte stage

Mosses

Most  mosses  are  not  mosses?Reindeer  moss

Scale  moss

Club  moss

Spanish  moss

Sea/  Irish  moss

Mosses

Three  groupings  of  mossesPeat  mossesGranite  mossesBryidae mosses

Bryidae are  the  closest  relatives  to  vascular  plants

Peat/  Spaghnum

Distinctive operculum/  pseudopodiumsporophyte

Cellular  structure  allows  for  incredible  water  retention

Peat  Ecology

Peat  bogs  occupy  roughly  10%  of  terrestrial  surfaceMakes  peat  one  of  the  most  abundant  plants  on  earthStores  ~400  billion  tons  of  carbonLocations  in  temperate/  boreal/arctic  and  anoxic  conditions  makes  bogs  carbon  sinks

True  Mosses

Class  BryidaeReduction  in  gametangia

Sessile  and  apical  (compare  to  Marchantia)

Have  primitive  vascular  cellsHadrom water  conductionLeptoids sugar  conducting

True  Mosses

Evidence  of  insect  interactions  at  two  different  stages  of  moss  reproduction

Brightly  colored  sporophytes may  facilitate  insect  mediated  dispersal  of  sporesBrightly  colored  bracts  on  the  tops  of  gametophytes  may  facilitate  movement  of  sperm