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Marcelo Botello 2/21/11 Per. 7. Bryophytes. What are Bryophytes?. Bryophytes are embryophytes, land plants, that are non-vascular , which means that they lack particular tissues that circulate fluids and nutrients internally.
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Marcelo Botello 2/21/11 Per. 7 Bryophytes
What are Bryophytes? • Bryophytes are embryophytes, land plants, that are non-vascular , which means that they lack particular tissues that circulate fluids and nutrients internally. • They reproduce via spores, which are reproductive structures that move away from the parent organism from one habitat to another in unfavorable conditions.
Classification • Bryophytes consist of three separate groups: • Liverworts: leafy plants in which cells of the plant carry only a single set of genetic information. • Hornworts: group of bryophytes that tend to grow in large numbers in places that are damp. • Mosses: small, soft plants that usually grow close together in clumps. • The term, bryophyte, refers to a shared structure.
Liverworts Broad and thin structures Get their name from the fact that they resemble the shape of a liver. Produce structures that look like green umbrellas, which is where the structures that produce eggs and sperm are located. They can reproduce asexually.
Hornworts Looks like a tiny green horn Found in damp soil Resemble liverworts
Mosses Most common bryophytes Produce thin stalks Lose water quickly if surrounding air is dry
Bryophyte sexuality • These plants are generally gametophytes, which are cells that contain only a single set of chromosomes. • They have two basic categories of sexuality: • Dioicous: bryophytes that only produce male/female organs on a single plant body. • Monoicous: bryophytes that produce both male and female organs on the same plant body.
Dioicous Monoicous Dicranum scoparium Benincasa
Where they live and why • Bryophytes live in a moist environment because they lack vascular tissues, so they are unable to transport water over long distances. • That is why they grow short to that ground of a moist environment where water is available to them.
Characteristics • They neither have flowers, nor produce seeds. • They are very short plants • the green tissue that makes up most of the plant body is not vascularized • They do not have roots, instead they have rhizoids, which anchor the plant and facilitate water and nutrient uptake.
Life cycle • Summary: -Zygote forms into a developing sporophyte, then when it matures, it releases spores, and the rhizoids form. -The gametophyte is the dominant stage of the life cycle, and is the stage that carries out most of the plants photosynthesis.
Dependence of water • For fertilization to occur, the sperm of a bryophyte must swim to an egg. • Sometimes, raindrops can splash sperm from one plant to another. • Because of the limit to reproduction, they MUST live in a habitat where water is available to them.
Life cycle of a Moss • When a moss spore lands in a moist place , it germinates and grows into a mass of tangles green filaments called protonema. • As the protonema grows, it forms rhizoids. • When the whole life cycle is complete, the spores are scattered to the wind to start the cycle again.
Human uses of moss • Sphagnum mosses act as a sort of natural sponge, because they can absorb many time their own weight. • Peat mosses can be cut from the ground and burned as fuel. • Peat moss is also used in gardening because it improves the soils ability to retain water.
