Bryophyte Reproduction

Bryophyte Reproduction

Some basic information on the sexual reproduction of bryophytes
These pages will be completed as a part of the Madbryo project, focusing on Malagasy plants.

The bryophyte life cycle alternates between two generations

A chlorophyllose generation producing sexual cells called the gametophyte

  • The gametophyte: a reproductive stem with leaves or a thallus bearing differentiated organs called gametangia where sexual cells (gametes) are formed.
  • Male gametangia are called antheridia and contain flagellate mobile male sexual cells (spermatozoids).
  • Female gametangia are called archegonia and one sexual cell, the oosphere (or egg) is retained in the body of the archegonia.

The sporophyte — a generation that produces spores and remains attached to the gametophyte

Main differences between the sporophytes of the three bryophyte lineages (liverworts, mosses and hornworts) :
  • Liverworts (Marchantiophyta): 
    • The seta is fleshy and the sporophyte is short lived (one day to a few days).
    • The capsule opens mostly via four valves and the spores are disseminated with the help of spiral cells called elaters. Some exceptions (e.g. Riccia spp. have no elaters, and no valves)
  • Mosses (Bryophyta sensu stricto) 
    • The capsule of mosses contains a central column of tissue called the columella
    • The capsule is protected by a calyptra derived from gametophytic tissue. The calyptra can have various forms depending on the genus or species.
    • The opening of the capsule varies by taxonomic group and the dispersal of spores is often mediated by a complex structure called the peristome.
  • Hornworts (Anthocerotophyta)
    • The sporophyte takes the form of a long stalk or "horn" that splits longitudinally
    • Hornwort sporophytes have a columella like mosses but also contain pseudo-elaters that a function similar to the elaters of liverworts 

  • City skyline

    Liverwort capsule detail showing spores and elaters. Pellia epiphylla, a thalloid liverwort not reported for Madagascar.

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    • A diagram illustrating how the life cycle of bryophytes alternates between the two generations

    bryophytes life cycle

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