Bryophyta, the division of green plants, refers to embryophytes which in literal term is land plants specially 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 do not have true vascular tissue. Some do have specialized tissues which is 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 ever evolved.Characteristics of Bryophytes
- 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.
Bryophytes have life cycles like all 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 forms by the fusion of haploid sperm and eggs produced by gametophytes. Diploid zygotes grows into a sporophyte.
Sporophytes’ characteristics of the three groups of bryophytes
|Capsule form||Simple||Differentiated (operculum, peristome)||Elongated|
|Dehiscence||Longitudinal or irregular||Transverse||Longitudinal|
|Dispersion of spores||Elaters||Peristome teeth||Pseudo-elaters|
|Maturation of spores||Simultaneous||Simultaneous||Graduate|
|Structure||Small, without chlorophyll||Large, with chlorophyll||Large, with chlorophyll|