Bryophytes

What are Bryophytes?

Bryophyta, the division of green plants, refers to embryophytes which in literal terms, are land plants, especially the non-vascular ones. This division includes-

  • Mosses – class Bryopsida
  • Liverworts – class Marchantiopsida
  • Hornworts – class Anthocerotopsida

The only prime feature of a bryophyte is that it does not have true vascular tissue. Some do have specialized tissues which are used to transport water, but are not considered to be a true vascular tissue due to the lack of lignin.

Bryophytes are believed to evolve from charophytes and are considered to have been the first true plants to have ever evolved.

Characteristics of Bryophytes

As stated before, the defining feature of bryophytes is that they are non-vascular plants. Other important bryophytes characteristics are as follows:

  • Plants in this category do not have roots but have crude stems and leaves.
  • They have “rhizoids” instead of roots which helps the plant to anchor to surface.
  • These roots or rhizoids do not absorb nutrients like other usual plant roots.
  • Mosses release spores from their leaves which travels by water and make new mosses in new locations.
  • Water is very essential for mosses to grow and spread. They can entirely dry out and survive. When in contact with water, they again revive and continue growing.

The life cycle of Bryophytes is like all the other land plants (embryophytes) with alternation of generations. A haploid gametophyte cell contains a fixed number of unpaired chromosomes. It gives rise to diploid sporophyte, which, however, contains twice the number of paired chromosomes. Diploid zygotes formed by the fusion of haploid sperm and eggs produced by gametophytes. Diploid zygotes grow into a sporophyte.

Sporophyte Characteristics of the three groups of Bryophytes

LiverwortsMossesHornworts
Capsule formSimpleDifferentiated (operculum, peristome)Elongated
ColumellaAbsentPresentPresent
DehiscenceLongitudinal or irregularTransverseLongitudinal
Dispersion of sporesElatersPeristome teethPseudo-elaters
GrowthDefinedDefinedContinuous
Maturation of sporesSimultaneousSimultaneousGraduate
PersistenceEphemeralPersistentPersistent
SetaPresentPresentAbsent
StomataAbsentPresentPresent
StructureSmall, without chlorophyllLarge, with chlorophyllLarge, with chlorophyll

Conclusion

Bryophytes are an informal division that consists of 3 groups of non-vascular plants, namely mosses, liverworts, and hornworts.  Prominent bryophytes characteristics are the absence of true roots stems and leaves. Furthermore, rhizoids perform the function of roots, essentially anchoring the plants into the surface. Though, rhizoids do not absorb nutrients like traditional plant roots.

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