Habitat of lycophytic plants. Lycopods, horsetails and pteridophytes
The lycophytes are the most ancient group of modern higher plants; fossil remains of plants of the genus Moss are known from the end of the Silurian - the beginning of the Upper Devonian of the Paleozoic era (approximately 380 million years ago). In the Paleozoic, lycophytes flourished, reached enormous sizes (up to 40 m), and occupied a dominant position in the vegetation cover of the Earth. Currently, this is a dying group of plants. All modern lycophytes are herbaceous plants, numbering approximately 1 thousand species. These are the very first vascular plants: in addition to well-developed leafy shoots, they have true roots. The lycophytes are characterized by microphyly, i.e. relatively small leaf sizes. The leaves of the lycophytes arose as superficial outgrowths on axial organs, making them a unique group. The stem is well developed, the leaf arrangement is spiral, opposite and whorled; branching is dichotomous. Young shoots grow due to the apical meristem, the activity of which fades over time and therefore lycophytes are limited in growth. Lycopods do not have a main root. Adventitious roots extend from the underground rhizome.
In the life cycle, the sporophyte (adult plant) predominates over the gametophyte. Sporangia in lycophytes are formed on specialized spore-bearing shoots - strobili in the form of spikelets. The gametophyte is small in size, called a prothallus, which dies immediately as soon as a new sporophyte is formed from it. An aqueous environment is required for fertilization of an egg.
There are two classes within the department: Moss-moss and Half-moss.
The class Lycophytes unites homosporous plants. Modern lycophytes are represented by one order, one family Moss and two genera: moss and phylloglossum.
In lycophytes, bisexual underground or semi-underground growths (gametophytes) mature within 1 to 15 years. Plants lack a cambium. The genus clubmoss includes approximately 200 species, usually representatives of tropical and subtropical forests. In the tropics, the vertical stems of lycophytes reach 1.5 m in height.
A typical representative of the green moss coniferous forests of the temperate zone of the Northern Hemisphere is the club moss. This is an evergreen perennial herbaceous plant with a creeping stem reaching 3 m in length. The stem is covered with small linear-lanceolate leaves. Attached to the ground by lateral roots, externally similar to adventitious roots, living for 2-5 years. Low vertical lateral shoots with dichotomous branching extend from the creeping stem. At the ends of the side shoots there are spore-bearing spikelets. The spikelet consists of sporolists (sporophyll), at the base of which there is a sporangium with spores. The spores have a triangular shape. On the outside, they are covered with a mesh pattern as a result of thickening of the spore walls. When spores germinate, bisexual shoots develop very slowly (up to 18 years). The prothallus is a whitish nodule up to 2 cm in diameter. Antheridia and archegonia are formed on the prothallus. After fertilization, a young sporophyte develops from the zygote - an asexual generation, on which spores are subsequently formed.
Moss moss spores are used in medicine to sprinkle on pills and as baby powder. In large quantities they are a light yellow powder, velvety, greasy to the touch. This powder prevents the pills from sticking together. In the metallurgical industry, molds were previously sprinkled with this powder when smelting cast iron.
You need to collect spikelets with spores very carefully, without damaging the plant itself, especially the root system, since the plant recovers very slowly
Some mosses are poisonous (common moss).
The class Polushnikovae includes heterosporous herbaceous plants. Some species have vessels in the conducting tissue. Of the modern living Polushnikovs, there are two orders in the class: Selaginella and Polushnikov.
In the order Selaginellaceae there is one family Selaginellaceae with one genus Selaginella. Most species are small in size - 5-15 cm, with delicate creeping shoots, grow under the canopy of moist forests, forming green cushions similar to moss. There are forms with climbing and climbing shoots reaching a length of 20 m. Plants in open, dry habitats have an erect stem from 20 cm to 3 m in length. In species with a creeping stem, the leaves are arranged in 4 rows: larger leaves in the lower two rows, and smaller leaves in the upper two. They attach to the soil with the help of thin dichotomously branched roots, which are formed on special organs - rhizophores (rhizophores). Erect selaginella have small leaves (0.5 - 5 mm in length), spirally arranged along the stem. The mosaic of leaves allows for better light capture. Some Selaginella are epiphytic plants.
Selaginella are heterosporous herbaceous plants. During asexual reproduction, micro- and macrospores arise in microsporangia on micro- and megasporophylls, in most cases located on the same strobile in the shape of a spikelet. The spikelet can occupy different positions. Germination of micro- and macrospores begins inside the sporangia. When a microspore germinates, a highly reduced germ is formed. During the first division, two unequal cells appear: the small one is prothallial (the remnant of the vegetative body of the prothallus), the large one is antheridial. The antheridial cell gives rise to the antheridium, where numerous biflagellate sperm are formed. By the time the cell matures, the walls of the antheridium and prothallial cells blur, and spermatozoa float in the general mass of the cytoplasm. This will be the male gametophyte, similar to a speck of dust from seed plants. Female shoots develop from megaspores. The tissue of the prothallus is multicellular, and after the membrane of the megaspore ruptures, the prothallus protrudes outward, its cells turn green and rhizoids form on it. In some species, this shoot can fall out, fall to the soil under favorable conditions and attach to it with the help of rhizoids. Rhizoids perform the function of absorbing water necessary for fertilization. In this case, the female thallus feeds on its own. In other species, the female gametophyte remains on the megaspore, and then the rhizoids perform the function of trapping dust particles; in this case, the female gametophyte lives at the expense of the mother plant. In both cases, after fertilization of the egg, an embryo develops, which consists of a stalk, leaves and rhizophore, on which roots subsequently form. The formed embryo begins independent life.
Slide 2
Description and habitats
Evergreen plants with recumbent or erect stems and small scale-like leaves. They live in coniferous trees, less often in mixed forests, where it is quite humid and the ground is covered with a continuous carpet of mosses.
Slide 3
Moss is one of the most ancient plants on Earth
- Many millions of years ago, powerful plants - tree ferns, huge, tens of meters high, horsetails and mosses covered the earth.
- Moss mosses originated in the Devonian period of the Paleozoic era.
Slide 4
Mosses reproduce by spores
- The spores are found on the underside of the “leaves” of the spikelet. At the end of summer, the spikelets turn yellow, and the ripe spores spill out onto the ground. It will take at least 10-12 years for a stem to form from a shoot that has sprouted from a spore.
- Moss clubmoss
Slide 5
Reproduction of club mosses
However, the above-ground stem is not a real plant: another 10-15 years must pass for the very same moss to grow, which each of us can without hesitation pick off as we pass by, bring it home, and then throw it away. Just think - the moss has been growing for three decades, but you can destroy it in three seconds!
Slide 6
Types of club mosses
Moss crimson (Vulgaris crimson) is a perennial evergreen plant. Stems are erect or ascending, 20-25 cm high, branching from the base. The leaves are multicore, narrow, rigid, entire or slightly serrated. The sporangia are not collected in spikelets, but are located in the axils of the leaves; sometimes viviparous buds are formed instead of them. The spores ripen in July-August. Poisonous. It grows from 1 to 4 cm per year.
Slide 7
- Moss annual
- Moss oblates
Slide 8
The meaning of club mosses
- Moss mosses are used to make medicines.
- Moss moss spores, rich in fatty oils, were previously used in pyrotechnics to produce explosives and lighting effects in the theater.
- Moss mosses are used in the treatment of nicotineism, alcoholism, and eye diseases; however, self-medication can lead to death.
- Green, blue and yellow paints are obtained from club mosses.
- In medicine, spore powder is used as baby powder.
- Some types of club mosses contain a strong paralyzing poison, similar in nature to the poison of curare.
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In terms of their life cycle features, lycophytes and horsetails resemble ferns: individuals of the asexual generation have shoots and roots. Individuals of the sexual generation (thralls) are small in size and exist separately from individuals of the asexual generation.
Reproduction. In the development cycle of horsetails and club mosses, sexual reproduction using gametes and asexual reproduction using spores alternate. One plant can produce several million spores. All of them retain the ability to germinate for a very long time in a moist, warm environment.
Under favorable conditions, a small plate, a prothallus, develops from the spore. Soon, on the lower surface of the growth, in special organs - gametangia - male and female reproductive cells (gametes) are formed. With the help of water (when snow melts, with rainwater), male gametes (sperm) are delivered to the eggs. After fertilization, a green shoot with leaves is formed from the zygote. Over time, it develops into a large green plant that lives for many years. On the leaves of the plant, spores are formed in special organs - sporangia. Therefore, this stage of the life cycle of horsetails and club mosses is called sporophyte, and the growth stage is called gametophyte. The sporophyte is a perennial stage in their development, and the prothallus (gametophyte) lives for several days.
Gametophyte is the haploid multicellular phase in the life cycle of plants and algae that develops from spores and produces sex cells, or gametes. Develops from haploid spores. On the gametophyte, germ cells, or gametes, develop in special organs called gametangia.
Sporophyte is a diploid multicellular phase in the life cycle of plants and algae that develops from a fertilized egg or zygote and produces spores. Develops from a fertilized egg, or zygote. On the sporophyte, in special organs - sporangia - haploid spores develop as a result of meiosis. In many plants (heterogeneous mosses and heterosporous ferns, as well as gymnosperms and flowering plants), sporangia are divided into two types: macro- and microsporangia. Macrosporangia produce macrospores, and microsporangia produce microspores. Female gametophytes develop from macrospores, and male gametophytes from microspores.
In horsetails and club mosses, the gametophyte is a small but independent plant, sometimes called a prothallus. Thickets of ferns and horsetails are photosynthetic, annual. Moss moss growths live underground, develop over many years and feed through symbiosis with fungi.
In the life cycle of lycophytes and horsetails, as in pteridophytes, individuals of the asexual generation predominate. The differences between the representatives of these departments lie primarily in the structure of the vegetative organs.
Department Lycopods.
Club moss (Lycopodium clavatum)
Moss mosses are united in the order of higher spore plants. These are perennial evergreen herbaceous plants. According to the classification, clubmosses are divided into two families: clubmosses and ramaceae. The main characteristic of plants belonging to the lycophytes is the spikelets (strobilae) of sporangia. A distinctive feature of Barantsovye is that they have twice or four times dichotomously branched stems with axillary sporangia that are not packed into spikelets.
The clubmoss family includes four genera, which include 200 species. In the Barants family there is one genus, the club moss, which consists of 150 species.
In our country, club mosses can be found in green moss coniferous forests. These are representatives of the genera of clubmosses, for example, the annual clubmoss and club-shaped clubmoss and the common ram.
Mosses are the oldest group of plants. These plants flourished in the Paleozoic. Currently, mosses grow almost everywhere on our planet. The most numerous group of club mosses is represented in the forest zone of the northern hemisphere. These are homosporous perennial herbaceous plants, mostly terrestrial, with entire leaves. Mosses form shoots with adventitious roots. Shoots can be erect, creeping, climbing, their length reaches 10 m. Mosses at the age of 200-300 years can reach a diameter of 40 m or more. A characteristic feature of some types of clubmosses (oblate, club-shaped), which grow on depleted soils in pine forests and heather heaths, is the formation of “witch’s rings”.
The importance of mosses in human life is very great. Moss mosses have been used in medicine and veterinary medicine since ancient times. In industry, these plants are used to produce blue, green and yellow dyes. Moss mosses have found their application in shaped casting and pyrotechnics. The tissues of some types of mosses contain a potent poison, so you need to be careful when choosing a traditional medicine and not self-medicate.
Section Horsetails.
Horsetail
Like all higher spore plants, the sporophyte predominates in the life cycle of horsetails.
Modern horsetails are perennial herbaceous plants. All of them belong to the genus Horsetail, which includes over 30 species. Individuals of the asexual generation have well-developed rhizomes and roots. With the help of rhizomes, horsetail reproduces vegetatively. Aboveground shoots extend from the rhizome, ranging in height from 10 cm to 4–5 m (in some tropical species). The main stem branches; on the side stems you can see small wedge-shaped leaves devoid of chlorophyll. Photosynthesis occurs in green stems: main and lateral.
The most common species in Siberia are the outwardly similar horsetail and meadow horsetail. They are found along river banks, in meadows, in fallow lands, and thickets of bushes, like weeds in crops. Horsetail is also common in forest communities. In the Krasnoyarsk Territory they are found from the southern borders to the Arctic, and meadow horsetail - even to the coast of the northern seas of the Arctic Ocean basin. Another common species is horsetail. Mostly confined to natural habitats. Often found in forests, meadows, and along the edges of swamps. Horsetail tissues contain a lot of silicon dioxide, so they are very tough and inedible for many animals.
Some types of horsetail are used medicinally as a diuretic. Horsetails are excellent indicators (bioindicators) of soils with high acidity. By the beginning of the 20th century, horsetails were used to dye fur gray-yellow. In some areas, young spore-bearing shoots and starch-rich expanded rhizomes - “tubers” - of horsetail are eaten. For animals, all parts of horsetails are poisonous, as they contain substances that destroy some vitamins in their body.
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Moss-moss
Another division of higher spore plants is the lycophyta. Despite some similarities with mosses, mosses are true vascular plants. In the modern flora they are represented by three orders: lycophytes, selaginellae, polusniaceae - and almost 1000 species, distributed throughout the globe.
In modern forms of club mosses, the leaves are relatively small and arranged in a spiral around a creeping or ascending stem.
Branching rhizophores, similar to roots, extend down from the stem. Spores (in some forms the same, in others - different sizes) are formed on the upper side of sporophylls, collected in vertical spikelets or cones. Like ferns, moss spores form germs (gametophytic generation) with antheridia and archegonia; after fertilization, sporophytes sprout from the zygotes on the germs, and the cycle repeats again.
Lycopods have been known since Silurian. In the Devonian, ancient lycophytes died out: drepanophicus, prolepidodendron, cyclostigma. The heyday of lycophytes occurred in the Carboniferous, when the land was covered with forests of tree-like lepidodendrons and sigillaria up to 30 m high. The remains of dead plants formed layers of fossil coal. Starting from the Triassic, the ancient lycophytes began to gradually disappear from the face of the Earth.
Department Lycopods.
The lycophytes are the oldest group of modern higher plants; fossil remains of plants of the genus lycophyte are known from the end of the Silurian - the beginning of the Upper Devonian of the Paleozoic era (approximately 380 million years ago). In the Paleozoic, lycophytes flourished, reached enormous sizes (up to 40 m), and occupied a dominant position in the vegetation cover of the Earth. Currently, this is a dying group of plants. All modern lycophytes are herbaceous plants, numbering approximately 1 thousand species. These are the very first vascular plants: in addition to well-developed leafy shoots, they have true roots. The lycophytes are characterized by microphyly, i.e. relatively small leaf sizes. The leaves of the lycophytes arose as superficial outgrowths on axial organs, making them a unique group. The stem is well developed, the leaf arrangement is spiral, opposite and whorled; branching is dichotomous. Young shoots grow due to the apical meristem, the activity of which fades over time and therefore lycophytes are limited in growth. Lycopods do not have a main root. Adventitious roots extend from the underground rhizome.
In the life cycle, the sporophyte (adult plant) predominates over the gametophyte. Sporangia in lycophytes are formed on specialized spore-bearing shoots - strobili in the form of spikelets. The gametophyte is small in size, called a prothallus, which dies immediately as soon as a new sporophyte is formed from it. An aqueous environment is required for fertilization of an egg.
There are two classes within the department: Moss-moss and Half-moss.
The class Lycophytes unites homosporous plants. Modern lycophytes are represented by one order, one family Moss and two genera: moss and phylloglossum.
In lycophytes, bisexual underground or semi-underground growths (gametophytes) mature within 1 to 15 years. Plants lack a cambium. The genus clubmoss includes approximately 200 species, usually representatives of tropical and subtropical forests. In the tropics, the vertical stems of lycophytes reach 1.5 m in height.
A typical representative of the green moss coniferous forests of the temperate zone of the Northern Hemisphere is the club moss. This is an evergreen perennial herbaceous plant with a creeping stem reaching 3 m in length. The stem is covered with small linear-lanceolate leaves. Attached to the ground by lateral roots, externally similar to adventitious roots, living for 2-5 years. Low vertical lateral shoots with dichotomous branching extend from the creeping stem. At the ends of the side shoots there are spore-bearing spikelets. The spikelet consists of sporolists (sporophyll), at the base of which there is a sporangium with spores. The spores have a triangular shape. On the outside, they are covered with a mesh pattern as a result of thickening of the spore walls. When spores germinate, bisexual shoots develop very slowly (up to 18 years). The prothallus is a whitish nodule up to 2 cm in diameter. Antheridia and archegonia are formed on the prothallus. After fertilization, a young sporophyte develops from the zygote - an asexual generation, on which spores are subsequently formed.
Moss moss spores are used in medicine to sprinkle on pills and as baby powder. In large quantities they are a light yellow powder, velvety, greasy to the touch. This powder prevents the pills from sticking together. In the metallurgical industry, molds were previously sprinkled with this powder when smelting cast iron.
You need to collect spikelets with spores very carefully, without damaging the plant itself, especially the root system, since the plant recovers very slowly
Some mosses are poisonous (common moss).
The class Polushnikovae includes heterosporous herbaceous plants.
Division Lycopodiophyta – Lycopodiophyta
Some species have vessels in the conducting tissue. Of the modern living Polushnikovs, there are two orders in the class: Selaginella and Polushnikov.
In the order Selaginellaceae there is one family Selaginellaceae with one genus Selaginella. Most species are small in size - 5-15 cm, with delicate creeping shoots, grow under the canopy of moist forests, forming green cushions similar to moss. There are forms with climbing and climbing shoots reaching a length of 20 m. Plants in open, dry habitats have an erect stem from 20 cm to 3 m in length. In species with a creeping stem, the leaves are arranged in 4 rows: larger leaves in the lower two rows, and smaller leaves in the upper two. They attach to the soil with the help of thin dichotomously branched roots, which are formed on special organs - rhizophores (rhizophores). Erect selaginella have small leaves (0.5 - 5 mm in length), spirally arranged along the stem. The mosaic of leaves allows for better light capture. Some Selaginella are epiphytic plants.
Selaginella are heterosporous herbaceous plants. During asexual reproduction, micro- and macrospores arise in microsporangia on micro- and megasporophylls, in most cases located on the same strobile in the shape of a spikelet. The spikelet can occupy different positions. Germination of micro- and macrospores begins inside the sporangia. When a microspore germinates, a highly reduced germ is formed. During the first division, two unequal cells appear: the small one is prothallial (the remnant of the vegetative body of the prothallus), the large one is antheridial. The antheridial cell gives rise to the antheridium, where numerous biflagellate sperm are formed. By the time the cell matures, the walls of the antheridium and prothallial cells blur, and spermatozoa float in the general mass of the cytoplasm. This will be the male gametophyte, similar to a speck of dust from seed plants. Female shoots develop from megaspores. The tissue of the prothallus is multicellular, and after the membrane of the megaspore ruptures, the prothallus protrudes outward, its cells turn green and rhizoids form on it. In some species, this shoot can fall out, fall, under favorable conditions, onto the soil and attach to it with the help of rhizoids. Rhizoids perform the function of absorbing water necessary for fertilization. In this case, the female thallus feeds on its own. In other species, the female gametophyte remains on the megaspore, and then the rhizoids perform the function of trapping dust; in this case, the female gametophyte lives at the expense of the mother plant. In both cases, after fertilization of the egg, an embryo develops, which consists of a stalk, leaves and rhizophore, on which roots subsequently form. The formed embryo begins independent life.
The Polushnikov order includes one Polushnikov family with a single genus Polushnikov, represented by approximately 70 species. These are perennial herbaceous plants with a thick, erect stem and a rosette of linear subulate-shaped cylindrical leaves. At the base of the stem there is a rhizophore, from which the roots extend. On the upper surface at the base of the leaves there are numerous micro- and megasporangia. The gametophyte in Polusniaceae is even more reduced than in Selaginellaceae.
Polushnikov species are found in clean oligotrophic lakes and in desalinated shallow seas, and therefore can be classified as indicators of clean water.
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Topic: Mosses, horsetails, fernsTask 1. “Department Lycopods”
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Task 3. “Department Horsetails”Write down the question numbers and missing words (or groups of words):
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Look at the picture and answer the questions:
Task 5. “Department Ferns”Write down the question numbers and missing words (or groups of words):
Task 6. “Male shieldweed”Look at the picture and answer the questions:
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Task 7. “Reproduction of ferns”
Look at the picture and answer the questions:
- What is indicated in the figure by numbers 1 – 8?
- Where are gametes produced in ferns?
- How does sexual reproduction occur in ferns?
- Where do ferns produce spores?
- How does asexual reproduction occur in ferns?
- Where does the embryo of a new plant form in a fern?
Task 8. “Asexual and sexual generations of mosses, horsetails, ferns”
Look at the picture and answer the questions:
- Which generations of these plants are indicated by the letters A and B?
- Which plant organs are indicated by numbers 1 – 5?
- Why is the asexual generation called sporophyte?
- What is the sexual generation of these plants?
- Where are the embryos of a new plant formed in these plants?
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assignment 9. “Structure and reproduction
fern and moss"
Look at the picture and answer the questions:
- Compare the structure of fern and moss. What are the differences?
- What are fern sporophyte and moss sporophyte represented by?
- What is the fern gametophyte and the moss gametophyte?
Task 10. “Momps, horsetails, ferns”
Give a one sentence answer:
- From which group of algae did higher land plants originate?
- How many species are there of modern lycophytes, horsetails, and pteridophytes?
- What are the sporophyte and gametophyte of clubmoss?
- What are the sporophyte and gametophyte of horsetail?
- What are the sporophyte and gametophyte of the male shield plant?
- Are the shoots monoecious or dioecious in clubmoss, horsetail, and male shieldweed?
- When does meiosis occur in the cycle of club moss, horsetail, and male shield?
- Are club moss, horsetail, and male scale plant homosporous?
- Mosses, horsetails, ferns - which of these plants are only homosporous?
- Which plants have elater spores?
Answers:
Exercise 1. 1. Fading group, about 1000 species. 2. Roots, stems, leaves. 3. Tracheids; sieve tubes. 4. Sporophyte. 5. Dichotomous. 6. Microphilia. 7. Leafy plant. 8. Thickness; 6-15 years and more. 9. Monoecious or dioecious gametophytes. 10. Sporangia, which are located on the upper side of the sporophyll strobili. 11. Equal and heterosporous plants. 12. Selaginella and polushniki.
Task 2. 1. 1 – leafy shoot; 2 – adventitious roots; 3 – spore-bearing spikelet; 4 – prothallus; 5 – archegonia; 6 – antheridia; 7 – new plant in growth. 2. From a fertilized egg on the germ. 3. Monoecious. 4. When a dispute arises.
Task 3. 1. 25 types. 2. Tracheids; sieve cells. 3. Sporophyte. 4. Leafy plant. 5. Overgrowth. 6. Monoecious gametophyte. 7. Sporangia on sporangiosphores strobili. 8. To homosporous plants.
Task 4. 1. 1 – spring, spore-bearing shoot; 2 – vegetative shoot; 3, 4 – sporangiophores; 5, 6 – spores with wrapped and unfolded elaters; 7 – gametophytes; 8 - sperm. 2. Asexual - sporophyte, leafy plant, sexual - bisexual gametophyte. 3. Small, scaly, arranged in whorls. 4. They have elaters (hapters).
Task 5. 1. More than 10,000 species. 2. Tracheids; sieve cells. 3. Absent. 4. Vaii; sporulation and photosynthesis. 5. Macrophilic. 6. Herbaceous, tree-like, there are aquatic ferns. 7. Leafy plant, prothallus. 8. Absent.
Moss-moss
9. Monoecious outgrowth. 10. Sorusakh; indusium. 11. Bailout. 12. Equalsporus. 13. Aquatic ferns – marsilea, salvinia, azolla.
Task 6. 1. 1 – rhizome; 2 – adventitious roots; 3 – leaves (fronds); 4 – sporangia; 5 – prothallus; 6 - archegonia; 7 – antheridia. 2. A leafy plant, spores are formed in sporangia, reproduction by spores is asexual reproduction. 3. A prothallus on which gametes are formed in archegonia and antheridia; reproduction by gametes is sexual reproduction.
Task 7. 1. 1 – leafy plant; 2 – sporangia; 3 – development of a prothallus from a spore; 4 – prothallus; 5 – antheridia; 6 – archegonia; 7 – sperm; 8 – egg. 2. In the archegonia and antheridia of the prothallus. 3. Spermatozoa travel through the water into the archegonia and fuse with the eggs. A sporophyte develops from a zygote. 4. In the sporangia of the sporophyte. 5. With the help of spores from which shoots develop. 6. From the fertilized egg, the archegonium on the prothallus.
Task8. 1. A – asexual generation, sporophyte. B – gametophytes, sexual generation. 2. 1 – rhizome; 2 – adventitious roots; 3 – spore-bearing spikelet; 4 – sporangium; 5 – leaves. 3. Reproduction by spores is asexual reproduction, and leafy plants reproduce by spores. 4. Gametophytes, shoots. 5. On gametophytes, from fertilized eggs.
Task 10. 1. From green algae. 2. Lycophytes - about 1 thousand species, horsetails - 25 species, pteridophytes - 12 thousand species. 3, 4, 5. Sporophyte is a leafy plant, gametophyte is a prothallus. 6. In the moss moss it is monoecious, in the horsetail it is dioecious, in the male shield plant it is monoecious. 7. When a dispute arises. 8. Homosporous. 9. Only horsetails. 10. Horsetails.
Department of psilotophyta. Section lycophytes
Department of Psilotophytes
The psilotoid department includes one class - Psilotopsida, one order - Psilotales, one family – Psilotaceae, two kinds: psilot (Psilotum) And Tmesipteris.
Psilot is distributed in tropical and subtropical countries in both hemispheres. In Southern Spain, South Korea, Southern Japan, Hawaii, Southern USA. Includes two types. The sporophyte branches dichotomously, in the aerial part with small scale-like outgrowths and a branched underground rhizome-like formation with numerous rhizoids and endotrophic mycorrhiza. The psilot has a protostele. Identical spores appear in sporangia at the ends of short branches. When they germinate, they form a bisexual gametophyte, which develops in symbiosis with the hyphae of the fungus. Psilote spermatozoa are multiflagellate. The young sporophyte feeds on the gametophyte and later leads an independent lifestyle.
Tmesipteris represented by 10 species on the islands of Polynesia, New Zealand, Australia, and reaches the Philippine Islands. Tmesipteris, like psilot, are often epiphytes. It grows on the trunks of tree ferns, cycads and palm trees, at the base of tree trunks, on humus soil, or often in rock cracks.
Tmesipteris also lacks roots. Its underground organs are more or less dichotomously branched and rather long (up to 1 m or more) rhizome-like formations, which, unlike real rhizomes, are devoid of any scales, but are covered with numerous rhizoids. They are morphologically quite consistent with rhizomoids of rhinophytes.
Representatives of lycophytes
The cells of the outer cortex contain hyphae (endotrophic mycorrhiza).
In the above-ground part, the stems of Tmesipteris branch dichotomously and bear on the surface more developed cup-like appendages in comparison with the psilot.
In psilotaceae, sporangia form synangia. This indicates a certain evolutionary advancement of psilotids.
The gametophyte of the psilotaceae is brown, lacks chlorophyll, is a mycotroph; the hyphae of the fungus penetrate through the rhizoids into almost all cells.
The gametophyte has a radially symmetrical structure, is once or twice dichotomously branched and is very similar to a piece of rhizomoid 18 mm long and 2 mm in diameter. Its entire surface is covered with unicellular rhizoids. The internal differentiation of the gametophyte is very weak - sometimes an underdeveloped stele of tracheids surrounded by phloem and endoderm. Antheridia and archegonia are scattered throughout the surface of the gametophyte. Multiflagellate spermatozoa develop in the antheridia. Archegonia submerged, with a short protruding neck.
This is the oldest group of higher homosporous plants, which, in all likelihood, originated directly from rhiniophytes and has survived to this day. In their evolution, they advanced further than rhyniophytes along the path of specialization. They represent a closed branch in the evolution of higher plants
Department Lycopods
Zosterophyllophytes can almost certainly be considered the ancestors of lycophytes. The lycophytes reached their greatest development in the late Paleozoic. Currently, this department is represented by a small number of genera and species. Modern representatives are perennial herbaceous plants, usually evergreen. The fossils included both herbaceous and powerful woody forms. The lycophytes are represented by both homosporous and heterosporous plants.
From left to right: club moss, club moss, Selaginella selaginidae, lake moss
Gametophytes of homosporous living lycophytes are 2-20 mm in size. They lead a saprophytic or semi-saprophytic lifestyle. They mature within 1-15 years. Gametophytes of heterosporous lycophytes are unisexual and develop over several weeks due to the nutrients contained in the spore.
Reproductive organs: antheridia and archegonia. Bi- or multiflagellate spermatozoa are formed in antheridia, and eggs are formed in archegonia. Fertilization is possible in the presence of drip-liquid water.
The department includes two classes: club mosses (Lycopodiopsida) And half-shelled (Iso е topsida).
Class Mosses (LYCOPODIOPSIDA)
The class of lycophytes includes three orders: Asteroxylales, Lycopodiales And Protolepidodendrales. The first and third orders include completely extinct plants.
Order Asteroxylales
This order contains one family Asteroxylaceae ( Asteroxylaceae) and two kinds - Asteroxylon And Schizopodium. Both genera became extinct about 400 million years ago.
Asteroxylon (Fig. 18) was a herbaceous plant with above-ground and underground parts, stems and leaves. The leaves represented outgrowths of the stem (enation). Asteroxylon probably gave rise to higher plants with small leaves, a microphylic lineage in the evolution of higher plants. Its conducting system is the actinostele.
Order Lycopodiales
This order includes one family - Lycopodiaceae and two kinds: clubmoss (Lycopodium) And phylloglossum, which is found in Australia.
The genus clubmoss has about 400 species: In the CIS countries it is represented by 10-12 species, in the Republic of Belarus - 3 genera and 5 species.
Modern club mosses are small herbaceous plants.
Found in tropical forests Lycopodium volubile, reaching 9 m (liana).
Widespread in our country club moss (L. clavatum), growing in coniferous, often pine forests.
In the club moss, lateral roots emerge from creeping, dichotomously branching shoots that live for 2-5 years.
New roots arise only from the shoot apex meristem. When the meristem is dichotomized, the shoot and root arise simultaneously as the rudiments of two equivalent organs. If a root is formed on a plagiotropic shoot, then it immediately bends, goes deeper into the soil and looks like an adventitious one. If the root appears at the top of an orthotropic shoot, then it, also bending, moves along the bark along the entire shoot and emerges at its very base, all the more reminiscent of an adventitious root.
The initiation and development of the root and shoot as two equivalent organs is confirmed by the similarity of the anatomical structure of the stem and the basal part of the root itself. As the root deepens into the soil, its anatomical structure changes due to its specific habitat.
The stem and branches are densely covered with small linear-subulate leaves. The plant seems to float on the ground. Hence, probably, the name of the clubmoss.
The anatomical structure of the stem is still primitive. Young stems have a protostelic structure, while adults have a plectostelic structure. The outside of the stem is covered with epidermis. Next comes a powerful bark. The cells of the inner layers of the cortex have very thick walls and form a mechanical ring. The central part of the stem is occupied by a concentric vascular bundle (stele). The xylem in the bundle is arranged in the form of ribbons connecting to each other. Between the xylem sections and surrounding it from the periphery, phloem is located. There is no pith, there is no cambium in the bunch. Behind the phloem there is one layer of the pericycle, then the endoderm, which separates the bundle from the cortex.
In the bark of the stem there are leaf traces - bundles of conductive tissue going to the veins of the leaf. Adventitious roots with root hairs.
The leaves are covered on the outside with epidermis and stomata. Mesophyll is multilayered with intercellular spaces.
Sporulation in the moss moss is observed in mid-summer. Spore-bearing spikelets appear one at a time, less often two or three at the tops of the branches. Sporophylls are located on the axis of the spikelet. They are smaller than vegetative leaves, have a triangular-ovate shape, pointed, and yellow in color.
On the upper side of the sporophylls, kidney-shaped sporangia on a short stalk develop. Inside the sporangium, small identical spores are formed in large numbers from sporogenic tissue by meiosis. They have a rounded tetrahedral shape and a yellowish color. Spores have two membranes - exosporium and endosporium. The internal contents of the spore are composed of protoplasm, nucleus, plastids, and fat droplets. The mature sporangium is opened by a transverse fissure. By this time, the spikelet axis has expanded somewhat, the sporophylls are moving apart, and the spores are easily sown. On the surface of the earth, the spore is carried by currents of water into depressions (cracks) in the soil, where it germinates at a depth of several centimeters. A prothallus (bisexual gametophyte) is formed in the form of a lump of cells. The life of the prothallus is possible only with symbiosis of the fungal hyphae.
The mature growth has a cube-shaped shape, reminiscent of a toy top. Antheridia and archegonia are formed on the upper side of the prothallus. Antheridia are immersed in the tissue of the prothallus. Numerous biflagellate spermatozoa develop in them. The archegonia's abdomen is also immersed in the tissue of the prothallus. In the abdomen of the archegonium, an egg cell and a ventral tubular cell are formed. There are 6-8 tubular cells in the neck. Antheridia and archegonia usually do not develop simultaneously: at first the gametophyte functions as a male gametophyte, later as a female.
The fertilized egg divides and forms an embryo consisting of a pendulum, stalk, embryonic stalk, leaflet and root. In the first stages, the embryo is nourished by the nutrients of the germ. Moss growths develop very slowly. It takes 15-18 years from the germination of spores to the young sporophyte. In this regard, species of mosses require protection.
Included in the Red Book of the Republic of Belarus common ram (Huperzia selago), flooded lycopodiella (Lycopodiella inundata).
Moss mosses have practical applications. Moss moss spores are used as baby powder. They are poured into tablets. In metallurgy, when casting critical parts, molds are sprinkled with moss moss spores and used in pyrotechnics. In rural areas, club mosses are often wrapped around arches and portraits for decoration, which cannot be done due to the destruction of plants.
Class Polushnik (ISOTOЁPSIDA)
Polushnikovaceae include heterosporous perennial herbaceous plants. The class includes orders Selaginellales And half-shank (Iso е tales).
Order Selaginellales
The order includes one family selaginellaceae (Sellaginellaceae) with one family Selaginella). It contains up to 700 species native to tropical and subtropical regions. Few species are found in the temperate zone. In the CIS countries, 8 species of Selaginella are found.
In fossil form, Selaginellaceae are found from the Upper Carboniferous.
Selaginella are quite varied in appearance. There are creeping and erect forms. Their size ranges from 5-10 cm to 2-20 m in length. Adult plants (sporophyte) of Selaginella are very similar in appearance to the clubmoss.
Selaginella selaginelliformes (S. selaginoides) found mainly in temperate regions, sometimes reaching the Arctic. This is a perennial plant. It, like the club moss, has a dichotomously branched stem. The shoots are dorsiventral and bear four-rowed leaves: two rows of smaller dorsal leaves and two rows of larger ventral leaves. The small dorsal leaves do not shade the ventral leaves. Root bearers (rivophores) extend from the stem, and from them are adventitious, also dichotomously branched roots.
In comparison with the clubmoss, Selaginella also differs in other features. Its stem is covered on the surface with a single-layer epidermis. This is followed by the cortex, the outer layer of which acquires a mechanical character, and, finally, the conducting bundle (stele), located in the air cavity in a suspended state with the help of single-row green cells of trabecular filaments (endoderm cells). The leaves have a midrib. The outside of the leaf is covered with epidermis. Leaf cells have one or two lamellar chromatophores, like algae. Stomata on the underside of the leaf.
At the base of the leaf there is a group of loose cells (pad), to which trabecular tissue approaches from the stem, through which air enters the stem.
Selaginella- heterosporous plant. It forms micro-sporangia and mega-sporangia. Microspores develop in large numbers in microsporangia. Mega sporangia produce 4 large megaspores. However, some Selaginella species tend to reduce the number of megaspores to one.
Sporangia are located in the axil of sporophylls and are collected in spikelets.
Micro- and megasporangia are mostly in one spikelet. Then the microsporangia are in the upper part or in another row of the same spikelet, and the megasporangia are in the lower part or occupy another row.
When a microspore germinates on the ground or inside a microsporangium, a highly reduced male prothallus is formed. It does not leave the spore shell. During the first division of the microspore, 2 cells are formed - one small prothallial (rhizoidal) cell and a larger antheridial cell. The antheridial cell then divides to form an antheridium. Spermatogenic cells, as a result of subsequent division, form a large number of biflagellate sperm.
When the megaspore germinates, it forms a female varostok. More often this process takes place on earth. The core of the megaspore divides repeatedly, septa appear and a multicellular prothallus is formed that does not leave the megaspore. The cells rapidly divide and break through the membrane of the megaspore, protrude outward, and turn green. Rhizoids appear on it, and it leads an independent lifestyle. In the upper part of the female thallus, a few archegonia develop, immersed in the tissue of the thallus. Fertilization occurs during rain.
The fertilized egg divides. The upper cell forms a pendant. From the bottom, an embryo is formed from a stalk, leaves, stalk and rhizophore. With the help of the stalk, the embryo absorbs nutrients from the germ. Subsequently, the embryo begins to live independently and gives rise to an adult Selaginella plant.
In some Selaginella species, the development of seedlings and fertilization occurs on the mother plant. And only after this the megasporangium falls off.
A rare relict species from the Polushnik family has been included in the Red Book of the Republic of Belarus lake pommel (Iso e tes lacustris).
In the Selaginellaceae, as in all other groups of homosporous plants, a natural connection can be traced between homosporousness, equal sex of gametophytes and their significant reduction, which in seed plants has reached the highest degree. These three processes have important biological significance. In microsporangia, a large number of very small spores are formed, giving rise to highly reduced male gametophytes - dust particles, which are easily carried by the wind. The mass of gametophytes increases the efficiency of the sexual process. The high rate of development of male gametophytes and their significant reduction (cutinized microspore shell) provide them with protection from drying out. The small size of the male gametophyte helps to save plastic material.
In megasporangia, there is a sharp reduction in the number of megaspores to 4-1, combined with an increase in their size and nutrient content. This promotes the development of a larger, more viable female gametophyte, which is also located under the megaspore shell. After fertilization of the egg, a full-fledged embryo of a new sporophyte can form on this gametophyte. The dioeciousness of gametophytes provides the new generation with expansion and enrichment of genetic potential.
In the Upper Paleozoic (350-280 million years ago), lycophytes reached their peak. From the semi-shnikov class it should be noted lepidodendron, or scalewood (Lepidodendron), sigillaria (Sigillaria) from the Permian period, pleuromeia from the Mesozoic. These were powerful woody plants that participated in the formation of coal. At the end of the Paleozoic era and at the beginning of the Mesozoic, all large representatives of the lycophytes died out, giving way to more competitive gymnosperms. Small herbaceous lycophytes were able to survive not only the era of dominance of gymnosperms, but also successfully adapt in the future to life in complexly organized communities with a predominance of flowering plants.
The family (Isoеtaceae) in Belarus is represented by 1 genus and one species – the lake eelgrass (Isoеtes lacustris), included in the Red Book of our country.
Department of Plauna
General characteristics and features of distribution on the planet. Diversity. This department unites about 100 modern species that came to us from the Devonian period. Moss mosses originated from psilophytes and were widespread in the Paleozoic era, starting from the Silurian period. Modern mosses are perennial evergreen herbaceous plants with creeping stems. Tree forms of the department occupied a dominant position and created forests during the Carboniferous period.
Features of the structure and life processes using the example of the club moss. This representative is often found in coniferous forests on moist soils. This is a perennial evergreen plant. Its dominant generation is the sporophyte, which consists of a branched creeping stem from which extend additional roots and dichotomously branched shoots that end in spore-bearing spikelets. The flow is hard, small, linear, arranged in a spiral and very dense. Sporiferous spikelets consist of sporolists, near the base of which there are sporangia, where identical haploid spores are formed. Vegetatively, the club moss reproduces by parts of a creeping stem.
Moss-shaped plants: types, external characteristics, where they grow
Once in the soil, the spores germinate into a shoot (monoecious gametophyte) only after a few years. The prothallus has rhizoids and feeds saprophytically. The development of the embryo is promoted by internal mycorrhiza, but it develops very slowly, and only after 12-15 years do antheridia and archegonia form on it. After fertilization, a new evergreen plant, a sporophyte, develops from the zygote. In some species, the shoots are dioecious and develop spores from nutrients over several weeks.
The role of club mosses in nature and human life:
— aboveground vegetative organs form significant biomass, but some species contain alkaloids and therefore are not used by animals;
- moss spores, which contain non-drying oil, are used in medicine as baby powder and for skin lesions as a drying and analgesic;
- sometimes spores are used in the metallurgical industry during shaped casting to sprinkle the walls of the mold so that the parts are smooth and easy to remove;
— the use of clubmosses for making wreaths and garlands has led to a sharp decrease in the number of these plants, so they need careful treatment and protection.
Two Classes: Moss-moss and awl-shaped.
Moss-shaped. Moss mosses most often grow in coniferous or mixed forests. These are herbaceous plants with long stems creeping along the ground, densely covered with narrow green leaves. Roots and stems branch dichotomously. Vertical branches extend from the stem densely leafy shoots 20-30 cm high. At the top of such shoots, spore-bearing spikelets with sporangia develop. Spores are formed in sporangia, which are characterized by a long period of dormancy. The spores germinate in the soil in 3-8 years after eruption from sporangium. From dispute bisexual gametophytes develop - shoots that look like a small nodule (up to 5 mm). The nodules enter into symbiosis with fungi and feed saprotrophically. The shoots develop very slowly:after about 6-15 years, archegonia with eggs and antheridia with sperm are formed. Fertilization occurs in the presence of water. A fertilized egg - a zygote - germinates without a dormant period and forms a small sporophyte, which develops into an adult plant. The period from the formation of spores to the formation of an adult sporophyte is 12-18 years. In the life cycle, therefore, sporophyte predominates.
Modern lycophytes are mainly herbaceous plants. Extant forms like the club moss are distributed from the tropics to the tundra. The department includes 1200 species. There are 7 species growing in Belarus. Among them are club moss, oblate moss, annual moss, and ram. All species are protected. Modern club mosses are relict plants and do not have a significant role in the formation of vegetation cover. Their practical use is also limited. Dried moss spores (lycopodia) are used as baby powder; in the metallurgical industry - during shaped casting of metals. Moss moss is used to produce yellow paint.
Name the main classes of the Division Equisetaceae. Reveal the features of the habitat, structure, and reproduction.
Class Equisetaceae.
Horsetails. Herbaceous plants grow in wet fields and meadows, in swamps and damp forests - horsetails Although they differ in appearance from ferns, they are similar in characteristic features to them. Horsetails, like ferns, are higher spore-bearing vascular plants.
Horsetail. A typical plant of the horsetail division is horsetail. It grows in fields and arable lands. It is a perennial weed. In the soil there is an underground branched rhizome with adventitious roots and buds, from which above-ground shoots develop every year. A plant that has roots, rhizomes, and above-ground shoots is an asexual generation of horsetail - a sporophyte.
When cultivating the soil, horsetail rhizomes cut by a plow do not die, and an independent plant grows from each piece. This is why this weed is difficult to control.
Reproduction. In horsetail two types of shoots are formed. In early spring they emerge from the soil yellowish-brown, non-branching, spore-bearing shoots. In their cages no chlorophyll. Their ribbed stem consists of internodes that are easily separated from one another. Brownish scale-like leaves are located in whorls at the nodes, also lacking chlorophyll and incapable of photosynthesis.
The growth of spring shoots occurs due to organic substances stored in the rhizome. Spore-bearing spikelets are formed at the tops of these shoots. They are formed by hexagonal spore-bearing leaves, on each of which sporangia develop . After ripening, the spores disperse, and the spring shoots dry out and die. Two types of shoots grow from spores under favorable conditions. On some shoots, male organs of sexual reproduction - antheridia - develop, on others - female organs - archegonia, in which germ cells are formed. A prerequisite for fertilization is availability of water. Male gametes approach the prothalla with archegonia and fuse with the eggs. After fertilization, a young plant develops from the zygote.
On horsetails that have shed spring shoots, by the beginning of summer, branchy green summer shoots in the form of small fir trees develop from the buds of the rhizome. On the side shoots, located in regular whorls on the main stem, there are underdeveloped leaves - scales fused together. The stem is impregnated with silica, so it is very durable. The cells of the stem and lateral branches contain chloroplasts; photosynthesis occurs in them. The resulting organic substances flow into the rhizome and are stored there. In spring, organic matter is used not only for the growth of spore-bearing shoots, but also for the formation new rhizomes.
Variety and significance of horsetails. Currently, horsetails do not play a major role in the formation of plant cover, although they often form thickets in places where other plants cannot exist. . The variety of horsetails is quite large: from small creeping plants to large climbing plants, rising up to 9 m. Their species diversity is small. Horsetails are represented by one genus - horsetail, which includes about 30 species. 8 species are common in Belarus. All types of horsetails are herbaceous plants. In our forests, on very moist soil, horsetail with highly branched, drooping side branches is common. Overwintering horsetail is found on sandy soils and in ravines; marsh horsetail and riverine horsetail grow in wetlands, along the banks of rivers and lakes.
The shoots of some horsetails (for example, horsetail) are used in folk medicine as a diuretic and astringent. The hard stems of overwintering horsetail contain significant amounts of silica (a very hard, highly polishing substance). These stems have long been used for cleaning metal utensils and instead of sandpaper.
Lycopods are one of the most ancient divisions of higher plants. Currently, they are represented by a relatively small number of genera and species, the participation of which in the vegetation cover is usually insignificant. Perennial herbaceous plants, usually evergreen, resembling green mosses in appearance. They are found mainly in forests, especially coniferous ones.
Higher spore plants are the first terrestrial plants that live in moist places, often under the forest canopy, or in swamps, or in fields with acidic soils. Tree ferns, horsetails and clubmosses, which dominated in the Paleozoic, are now represented by herbs, with the exception of tropical tree ferns. Mosses have changed little during this period, since they occupy only their characteristic wet habitats. These plants require water to reproduce, since their gametes - sperm - are transferred to the eggs only in dripping liquid water, and the shoots can only grow in moist soil. Life in difficult land conditions led to selection for such adaptive characters as the formation of vegetative organs (root, stem, leaf), reproductive organs (archegonia, antheridia, sporangia), as well as tissues. In the food chains of past geological eras, higher spore plants occupied a leading place: they served as food for herbivorous amphibians and reptiles. Currently, their role as forage plants has noticeably decreased, but their importance in nature remains: they retain water in the soil, create conditions for the preservation and germination of seeds of gymnosperms and angiosperms, and provide a habitat for animals. In the human economy, the role of ancient tree-like forms is great, providing deposits of coal, which, like peat, serves not only as fuel, but also as a valuable chemical raw material. Among this group of plants, only horsetail is a difficult-to-eradicate weed in fields with high soil acidity. Higher spores are living fossils that have survived to this day, so they must be preserved and protected. The Red Book of the USSR includes 32 species of mosses and 6 species of ferns; The Red Book of the RSFSR contains 22 species of mosses, 10 species of ferns and 4 species of mosses. |
There are about 400 species, but only 14 are common in Russia (club-shaped moss, ram-moss, biacute moss).
Structure
Lycopods are characterized by the presence of shoots with spirally, less often oppositely and whorled leaves. The underground parts of the shoots of some lycophytes have the appearance of a typical rhizome with modified leaves and adventitious roots, while in others they form a peculiar organ bearing spirally arranged roots and called a rhizophore (rhizophore). Roots of lycophytes are adventitious.
Reproduction and nutrition
Sporophylls can be similar to ordinary vegetative leaves, sometimes different from them. Among the lycophytes there are equi- and heterosporous plants. Homosporous gametophytes are underground or semi-underground, fleshy, 2-20 mm long. They are bisexual, saprophytic or semi-saprophytic, and mature within 1-15 years. Gametophytes of heterosporous unisexuals, non-green, usually develop within several weeks due to the nutrients contained in the spore, and upon maturity do not protrude or protrude slightly outside the spore shell. The reproductive organs are represented by antheridia and archegonia: in the former, bi- or multiflagellate sperm develop, and in archegonia, eggs develop. Fertilization occurs in the presence of drip-liquid water, and a sporophyte grows from the zygote.
Sporophyte of club mosses is a perennial evergreen plant. The stem is creeping, branched, produces vertical branched shoots about 25 cm high, densely covered with leaves that look like elongated pointed scales. Vertical shoots end in spore-bearing spikelets or apical buds. On the shaft of the spore-bearing spikelet there are sporophylls with sporangia on the upper side. The spores are identical, contain up to 50% non-drying oil, and germinate very slowly. The gametophyte develops in the soil in symbiosis with a fungus (mycorrhiza), which, receiving carbohydrates, amino acids and phytohormones from the vascular plant, makes water and minerals, especially phosphorus compounds, available for absorption and absorption by the plant. In addition, the fungus provides the plant with a larger absorption surface, which is especially important when it grows in poor soil. The gametophyte develops over 12-20 years, has rhizoids, and does not have chloroplasts. However, in some species it develops on the soil surface, then chloroplasts appear in its cells.
