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Bryophyte - Classification, Characteristics, And Habitats Of Bryophytes, Hepatophyta (division Liverworts), Hornworts (division Anthocerophyta)

mosses cells called leaves

Bryophytes include the mosses, liverworts, and hornworts. Bryophytes are the simplest of plants (excluding the algae, which are not considered plants by most botanists). Bryophytes are small, seldom exceeding 6-8 in (15-20 cm) in height, and usually much smaller. They are attached to the substrate (ground, rock, or bark) by rhizoids, which are one or a few-celled, root-like threads that serve only for anchoring and are not capable of absorbing water and nutrients from the substrate. Brypohytes lack vascular tissue (the specialized cells grouped together to pipe water and nutrients to various parts of the body), or in the rare cases when this tissue is present, it is not well differentiated. The leaves of bryophytes are technically not true leaves, because in most species they lack vascular tissue. However, they are functionally equivalent to leaves, containing chlorophylls a and b for photosynthesis. Leaves are usually one-cell thick, except for the midrib, which may be up to 15 cells thick. Bryophytes satisfy their nutritional requirements by absorbing minerals from dust, rainfall, and water running over their surface.

The life cycle of bryophytes is characterized by an alternation of generations, one of which is a multicellular, diploid individual called a sporophyte, having two of each type of chromosome per cell. This stage alternates with multicellular, haploid individual called the gametophyte, with only one of each type of chromosome per cell, as is also the case with animal sperm. Bryophytes are unique among plants in that the dominant, conspicuous generation is the haploid gametophyte. In all other plants, the dominant stage is the diploid sporophyte.

Most reproduction of bryophytes is asexual, occurring by fragmentation of body parts, and by the production of specialized vegetative units called gemmae. Gemmae may be produced as microscopic plates (in the genus Tetraphis), as bulbils in the axils of leaves (in Pohlia), or as microscopic filaments (in Ulota). When sexual reproduction occurs, it always involves a flagellated sperm (produced in a specialized organ called an antheridium) that must swim through water to reach an egg located in a specialized, flask-shaped organ (the archegonium). The antheridia and archegonia are surrounded by a layer of sterile cells, which protects the sex organs from mechanical damage and desiccation.

The union of the sperm and egg results in a diploid zygote, i.e., a new sporophyte. This is nourished by the gametophyte and grows on it in a parasitic fashion, although the sporophytes of some bryophytes photosynthesize and make some contribution to their own growth. Initially, as the young sporophyte grows, the archegonium also enlarges. However, it ultimately fails to keep pace with the growth of the sporophyte and becomes detached from its base, forming a cap-like structure called a calyptra.


True mosses

One of the most distinctive features of true mosses involves the development of their gametophytes. Spores germinate to produce a characteristic mass of algal-like threads, called protonema, which looks like a loose ball of wool. Bud-like structures develop later, and give rise to the familiar leafy gametophyte. Although mosses are considered to be non-vascular plants, many true mosses in fact have a primitive vascular system consisting of a central strand of water-conducting cells called hydroids. Some also have specialized cells around the column of hydroids called leptoids, which function in the transport of carbohydrates, the products of photosynthesis. The stems of true mosses are more-or-less uniformly leafy and erect. Their leaves usually have a midrib, and their sporophytes possess capsules that are borne on stalks that are made of sporophytic tissue. Also, the capsules contain one or two rows of toothlike appendages (peristome) over the opening of the capsule, which are exposed when the lid is shed. This is by far the largest group of mosses.

Peat mosses

This is a small, but extremely important group of mosses, numbering about 350 species. Their stems are branched at nodes, with the nodes closely spaced at the tips, giving the plants a tufted appearance. Their gametophytes develop from the margins of plate-like protonema, in contrast to the filamentous protonema of true mosses. The leaves of peat mosses lack a midrib, and the bulk of the leaf mass is composed of large, translucent cells that are dead. These hyaline cells contain pores, allowing them to readily take up water. Some peat mosses can absorb an amount of water equal to 26 times their dry weight. Narrower, living cells that photosynthesize occur in networks between the hyaline cells. The sporophytes of peat mosses are distinct in that the stalk on which the capsule sits is part of the gametophyte and not the sporophyte itself as in the true mosses. The capsule also characteristically disperses its spores by a minute explosion. At maturity, the globular capsules begin to dry so that the middle portion contracts inward. The contraction produces great internal pressure on the air trapped inside, which eventually increases enough to blow off the lid with an audible pop, shooting the spores into the air. The capsules lack a peristome.


Granite mosses

This is the smallest group of mosses containing only about 100 species. Granite mosses are small, dark, tufted plants that grow on exposed rocks in alpine and arctic regions. Their leafy gametophytes arise from a lobed structure, rather than from a filamentous protonema. Their sporophytes generally are stalks that are derived from the gametophyte, as in the peat mosses. Their tiny capsules typically have four vertical sutures that split at maturity to release the spores. This method of spore dispersal is unique among the mosses.


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bryophyte

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Thanks for providing this information, which I will use in a term paper and also plan to try to convert my lawn from turf to moss!

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Bryophyte - Classification, Characteristics, And Habitats Of Bryophytes, Hepatophyta (division Liverworts), Hornworts (division Anthocerophyta)

mosses cells called leaves


Bryophytes include the mosses, liverworts, and hornworts. Bryophytes are the simplest of plants (excluding the algae, which are not considered plants by most botanists). Bryophytes are small, seldom exceeding 6-8 in (15-20 cm) in height, and usually much smaller. They are attached to the substrate (ground, rock, or bark) by rhizoids, which are one or a few-celled, root-like threads that serve only for anchoring and are not capable of absorbing water and nutrients from the substrate. Brypohytes lack vascular tissue (the specialized cells grouped together to pipe water and nutrients to various parts of the body), or in the rare cases when this tissue is present, it is not well differentiated. The leaves of bryophytes are technically not true leaves, because in most species they lack vascular tissue. However, they are functionally equivalent to leaves, containing chlorophylls a and b for photosynthesis. Leaves are usually one-cell thick, except for the midrib, which may be up to 15 cells thick. Bryophytes satisfy their nutritional requirements by absorbing minerals from dust, rainfall, and water running over their surface.

The life cycle of bryophytes is characterized by an alternation of generations, one of which is a multicellular, diploid individual called a sporophyte, having two of each type of chromosome per cell. This stage alternates with multicellular, haploid individual called the gametophyte, with only one of each type of chromosome per cell, as is also the case with animal sperm. Bryophytes are unique among plants in that the dominant, conspicuous generation is the haploid gametophyte. In all other plants, the dominant stage is the diploid sporophyte.

Most reproduction of bryophytes is asexual, occurring by fragmentation of body parts, and by the production of specialized vegetative units called gemmae. Gemmae may be produced as microscopic plates (in the genus Tetraphis), as bulbils in the axils of leaves (in Pohlia), or as microscopic filaments (in Ulota). When sexual reproduction occurs, it always involves a flagellated sperm (produced in a specialized organ called an antheridium) that must swim through water to reach an egg located in a specialized, flask-shaped organ (the archegonium). The antheridia and archegonia are surrounded by a layer of sterile cells, which protects the sex organs from mechanical damage and desiccation.

The union of the sperm and egg results in a diploid zygote, i.e., a new sporophyte. This is nourished by the gametophyte and grows on it in a parasitic fashion, although the sporophytes of some bryophytes photosynthesize and make some contribution to their own growth. Initially, as the young sporophyte grows, the archegonium also enlarges. However, it ultimately fails to keep pace with the growth of the sporophyte and becomes detached from its base, forming a cap-like structure called a calyptra.


True mosses
One of the most distinctive features of true mosses involves the development of their gametophytes. Spores germinate to produce a characteristic mass of algal-like threads, called protonema, which looks like a loose ball of wool. Bud-like structures develop later, and give rise to the familiar leafy gametophyte. Although mosses are considered to be non-vascular plants, many true mosses in fact have a primitive vascular system consisting of a central strand of water-conducting cells called hydroids. Some also have specialized cells around the column of hydroids called leptoids, which function in the transport of carbohydrates, the products of photosynthesis. The stems of true mosses are more-or-less uniformly leafy and erect. Their leaves usually have a midrib, and their sporophytes possess capsules that are borne on stalks that are made of sporophytic tissue. Also, the capsules contain one or two rows of toothlike appendages (peristome) over the opening of the capsule, which are exposed when the lid is shed. This is by far the largest group of mosses.

Peat mosses
This is a small, but extremely important group of mosses, numbering about 350 species. Their stems are branched at nodes, with the nodes closely spaced at the tips, giving the plants a tufted appearance. Their gametophytes develop from the margins of plate-like protonema, in contrast to the filamentous protonema of true mosses. The leaves of peat mosses lack a midrib, and the bulk of the leaf mass is composed of large, translucent cells that are dead. These hyaline cells contain pores, allowing them to readily take up water. Some peat mosses can absorb an amount of water equal to 26 times their dry weight. Narrower, living cells that photosynthesize occur in networks between the hyaline cells. The sporophytes of peat mosses are distinct in that the stalk on which the capsule sits is part of the gametophyte and not the sporophyte itself as in the true mosses. The capsule also characteristically disperses its spores by a minute explosion. At maturity, the globular capsules begin to dry so that the middle portion contracts inward. The contraction produces great internal pressure on the air trapped inside, which eventually increases enough to blow off the lid with an audible pop, shooting the spores into the air. The capsules lack a peristome.


Granite mosses
This is the smallest group of mosses containing only about 100 species. Granite mosses are small, dark, tufted plants that grow on exposed rocks in alpine and arctic regions. Their leafy gametophytes arise from a lobed structure, rather than from a filamentous protonema. Their sporophytes generally are stalks that are derived from the gametophyte, as in the peat mosses. Their tiny capsules typically have four vertical sutures that split at maturity to release the spores. This method of spore dispersal is unique among the mosses.


Additional Topics

Bryophyte - Classification, Characteristics, And Habitats Of Bryophytes
The classification of bryophytes has been controversial among botanists. Traditionally, the division Bryophyta has included the true mosses, liverworts, and hornworts. However, some scientists consider each of these groups sufficiently distinct to deserve their own division: Bryophyta for the mosses, Hepatophyta for the liverworts, and Anthoceratophyta for the hornworts. The latter view is followe…

Bryophyte - Hepatophyta (division Liverworts)
Hepatophyta means "liver plant" and refers to the body of some common species of liverworts, whose lobing is reminiscent of a liver. During Medieval and earlier times, many people followed the doctrine of signatures—a belief that the superficial resemblance of a plant to some part of the human anatomy indicated that the plant possessed medicinal properties related to the organ…

Bryophyte - Hornworts (division Anthocerophyta)
The hornworts are the smallest of the three groups of bryophytes with only about 100 species in six genera. Hornworts are especially diverse in the tropics, although Anthoceros occurs in temperate regions. Hornworts derive their name from their sporophyte, which has the appearance of a tapered horn. The sporophyte has a mass of undifferentiated tissue called a meristem at its base. The meristem ca…

Bryophyte - Mosses (division Bryophyta)
Only members of the division Bryophyta are considered "true" mosses. Many other plants and some algae are commonly called mosses, because they superficially resemble the true mosses, but they are not in fact even closely related to them. For example, Spanish moss (Tillandia uneoides) is a flowering plant in the pineapple family, Irish moss (Chondrus crispus) is a red alga that is col…

Bryophyte - Importance Of Mosses
Mosses are extremely important during the early stages of ecological succession. Succession begins with the generation of a new environment. This can occur, for example, by the formation of sand dunes, the exposure of land by deglaciation, or by the radical disturbance of a previously vegetated landscape as when an area is logged or burned by wildfire. In such cases, the ground becomes vegetated b…

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over 1 year ago

it is good info.about bryophyt I am Tewodros from the great ETHIOPIA

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over 1 year ago

what is the criteria for bryophytes classification into division?

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almost 2 years ago

no there are no specialized cells in bryophytes which are called vascular bundles

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about 2 years ago

Thank you!

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over 2 years ago

bryophytes

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7 months ago

thanks this information .they help people.

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7 months ago

thanks this information .they help people.