CHARACTERISTICS AND LIFE PROCESSES OF MOSSES
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CHARACTERISTICS AND LIFE PROCESSES OF MOSSES.
Mosses are small, simple green, seedless, nonvascular plants called Bryophytes.
They are simple plants because their roots, stems, and leaves lack a vascular bundle (xylem and phloem) and little or no strengthening tissue.
Moss grows in clusters to enable them to conserve water.
They are regarded as lower plants.
Biological Classification:
Phylum/Division Bryophyta
Reasons:
- Their leaves and stems lack vascular tissue.
- They are seedless and produce no flowers.
- Presence of a thalloid body.
- Presence of a dominant gametophyte.
- Presence of a capsule raised on a stalk
Class Musci
Reasons:
- The gametophytes grow from a protonema that may be prostrate or upright.
- The stem is surrounded by thin, spirally arranged leaf-like structures.
- They lack true roots, stems, and leaves.
- The sporophyte is small in size.
Typical examples are
- Brachymenium,
- Funaria,
- and Sphagnum.
THE GENERAL STRUCTURE OF MOSS
- Mosses are small plants that lack tissues for transporting water and nutrients.
- They are described as non-vascular because they do not have true roots, stems, and leaves.
- Root-like structures called rhizoids anchor them to their substrates and absorb water and nutrients.
- The leaves are simple, spirally arranged, and only a single cell thick with no cuticle, stomata, or internal air spaces.
- The rhizoids, “stem,” and “leaves” together constitute the gametophyte.
- The gametophyte produces a stalk called a seta, with a capsule having a cap called a calyptra at its tip.
- This constitutes the sporophyte.
Habitat:
- Moist or dump soil.
- As epiphytes or parasites on the branches of some forest trees
Mode of nutrition
- Photosynthetic
Reason:
- Because of the presence of chlorophyll.
Movement, Growth, Respiration, and Excretion in Moss.
- Moss grows through spore germination and sporophyte formation
- Growth of the protonema extends through the substrate, and intracellular movement happens by cytoplasmic streaming.
- Primarily, aerobic respiration occurs in mosses.
- They respond to environmental stimuli like nutrient availability, light, and humidity
- Mosses release metabolic waste into the environment through the surface since they have no specialized structure.
Reproduction processes in moss.
Sexual reproductive structure.
- Archegonium (female reproductive part)
- Antheridium (male reproductive part.
Asexual reproductive structure.
- A capsule which contains asexual spores.
THE LIFE CYCLE OF THE MOSS
The life cycle or growth process in Moss is an alternation of generations.
This means it involves two alternating generations, which are;
- the diploid sporophyte and
- the haploid gametophyte.
- The gametophyte, which is a haploid, is dominant to the sporophyte.
- The male organ is called antheridium, and the female the archegonium.
- The antheridium and the archegonium are borne at the tip of the gametophytes, or both the male and the female on the same plant.
- Antheridium produces sperm with two flagella called antherozoids.
- The archegonium produces an egg called the oosphere.
- The antherozoid uses the flagella to swim in a film of moisture/film of water and fertilizes an egg called an oosphere in the archegonium to form a diploid zygote.
- The zygote formed develops into a young plant called the sporophyte.
- The sporophyte is diploid and is made up of a stalk that bears a capsule. The sporophyte depends on the gametophyte for food.
- At maturity, the capsule produces haploid spores by meiosis.
- During the dry season, the capsule splits to release spores, which germinate during moist conditions to produce a protonema, which develops into the haploid gametophyte.
Reasons why moss is confined to a moist habitat.
- Moist habitat due to the absence of a cuticle.
- Moisture is also needed for fertilization. Thus, the sperm cells from the antheridium swim to the archegonium to fertilize the egg.
Adaptive features of moss to its habitat
- Presence of rhizoids for anchorage.
- The presence of a capsule raised on a stalk for easy dispersal of spores.
- Soft and flexible body.
- Seta, which supports the capsule.
Economic importance of Moss
- Weathering to form a soil
- Check erosion
- Source of fuel
- Early colonizers in succession
- Used as soil conditioners
- Are plant parasites
- Improve moisture content in the formation of roots during marcotting.
- Mosses are commonly used in horticulture as a substrate for the cultivation of orchids and other epiphytic plants.
- Mosses have been used as bio-indicators of environmental pollution, particularly for heavy metals.
- Mosses are used in carbon sequestration, where they absorb high amounts of carbon dioxide from the atmosphere.
- Mosses are used as traditional medicine to treat a variety of ailments, including respiratory infections, digestive disorders, and skin conditions.
Review Questions
- List the structures of the moss plant.
- Describe the life processes of the moss.
- Discuss the economic importance of mosses.
- What are the benefits of the presence of mosses in the environment?
