Bryophytes

The seedless plants known as bryophytes are the closest living relatives of early terrestrial plants. The first bryophytes (liverworts) developed some 450 million years ago, during the Ordovician period. Bryophyte fossil formation is improbable due to their lack of lignin and other resistant structures. Hence the fossil record is weak. Early bryophytes are credited with surviving spores shielded by sporopollenin. On the other hand, Vascular plants had spread over the continents by the Silurian epoch. Nonvascular plants must have existed before the Silurian period, according to this overwhelming finding.

General Characteristics

All of the visible vegetative organs of a bryophyte belong to the haploid organism, or gametophyte, which includes photosynthetic leaf-like structures, the thallus, stem, and the rhizoid that binds the plant to its substrate. The sporophyte is almost invisible. As a result, the gametophyte is the most common and well-known form, while the sporophyte only occurs for a short time. Bryophyte gametes have a flagellum that allows them to swim. Bryophytes have sporangium, which are multicellular sexual reproductive structures that are lacking in the majority of algae. The sporophyte embryo is likewise kept connected to the parent plant, protecting and feeding it. This is a distinguishing feature of land plants. The liverworts (Hepaticophyta), hornworts (Anthocerotophyta), and mosses are the three species of bryophytes (true Bryophyta).

Types of Bryophytic Plants

Liverworts

Liverworts (Hepaticophyta) are thought to be the closest relatives of the progenitor that migrated to land. Liverworts have colonized every terrestrial area and have evolved into over 7000 species. Lobate green structures are formed by liverwort gametophytes (the main stage of the life cycle). The shape of these leaves is comparable to the lobes of the liver, which is where the species’ name comes from. Liverworts have openings that allow gasses to flow through them. These aren’t stomata because they don’t open and close. The plant absorbs water from all sides and lacks a cuticle to prevent desiccation.

Mosses

More than 10,000 moss species have been identified. Their habitats range from the tundra, where they are the dominant plant, to the tropical forest understory. The thin rhizoids of tundra mosses allow them to attach to a substrate without penetrating the frozen soil. Mosses help prevent erosion, store moisture and minerals in the soil, and provide food and refuge for tiny animals and larger herbivores like the musk ox. Mosses are used to evaluate air quality because they are sensitive to pollutants. Copper salts are likewise toxic to them. These salts are a typical component of lawn moss-killing products.

Hornworts

Hornworts (Anthocerotophyta) are a type of bryophyte that has colonized a wide range of land environments, yet they are seldom far from a source of moisture. The major phase of a hornwort’s life cycle is the brief, blue-green gametophyte. The group’s distinctive trait is the thin, pipe-like sporophyte. Sporophytes develop from the parent gametophyte and continue to grow throughout the plant’s life. The hornworts have stomata, and the sporophyte has a lot of them. A single chloroplast can be found in each photosynthetic cell of the thallus. Meristem cells in the plant’s base continue to divide and increase the plant’s height. Many hornworts form symbiotic relationships with cyanobacteria, fixing nitrogen from the atmosphere.

Economic Importance of Bryophytes

• Bryophytes are known as land pioneers because they were the first plants to develop and colonize barren rocks and lands.

• Bryophytes help to keep soil from eroding. Because they grow densely, they act as soil binders. Mosses develop a mat or carpet-like texture when they grow in dense strands. 

• Mosses and lichens form soil slowly yet effectively. The acid released by lichens and mosses’ gradual death and decomposition contributes to soil creation. 

• Peat mosses convert the bank of a lake or a shallow body of water into solid soil that supports vegetation such as Sphagnum. Peat is a brown or black substance generated in bogs by the progressive compaction and carbonization of partially decayed dead vegetative debris and it is a major economic importance of Bryophytes. 

• Sphagnum moss, a common example of bryophyte, is a type of aquatic moss. It secretes specific acids into the water body while growing in it.

Conclusion

Bryophytes are non-vascular terrestrial plants that reproduce by drinking water. Land plants are divided into two groups: those with specific tissues for transporting water and other materials, known as vascular plants, and those without specialized tissues, known as nonvascular plants. Because bryophytes are non-vascular, they lack the necessary structures to grow roots, stems, and leaves. Bryophytes are small plants that grow to be one to two centimetres tall. They can’t grow taller because they lack the tissues other terrestrial plants have to offer structure and support. On the other hand, Bryophytes form a cushion-like covering over soil, rocks, tree trunks and leaves by growing close together.