Like the rest of land plants, the Bryophytes are Embryophytes (plants that produce an embryo) and they have traditionally been viewed as a distinct lineage from other land plants. Bryophytes and vascular plants evolved independently from the first land plants. Like the rest of the land plants, they evolved from green algal ancestors, closely related to the Charophytes. There are some 20,000 species of Bryophytes (Wilbraham, 2025) making them the most species-rich group of land plants after the flowering plants.
Bryophytes are tiny, moisture-loving plants forming a carpet on forest floors and tree trunks. They act like sponges storing water and releasing this gradually to their surroundings.
With it varied landscape and habitats, it is not surprising that about one third of the world’s Bryophyte species are found in Tropical America, with high levels of endemism (Gradstein et al., 2001).
Like other land plants, the Bryophytes:-
- have multicellular sex organs, i.e. the gametes are enclosed by a sterile jacket of cells
- are parenchymatous, not filamentous
- retain the zygote within the female sex organ where it develops
- have a waterproof coating of sporopollenin on the spores
Unlike other land plants, Bryophytes:-
- have no lignin usually
- are small, low-lying, (generally) moisture-loving plants
- have no roots, only filamentous rhizoids
Bryophytes are the ONLY land plants with a dominant gametophyte!
The sporophyte is parasitic on the gametophyte. This stems from the embryo being retained in the female sex organ of the gametophyte.
There are 3 groups of Bryophytes;-
- Mosses (~12,500 species)
- Liverworts (~7,000 species)
- Hornworts (~200 species) – NOT covered in this course
References
Wilbraham, J (2025) Mosses, Liverworts, and Hornworts of the World: A Guide to Every Order. Princeton University Press, Princeton & Oxford.