Basic characteristics of algae
The concept of algae is different from ancient times to modern times. China ancient book said: "gnats, aquatic plants, or algae." It can be seen that the algae in ancient China are the floorboard of aquatic plants. In modern botany in China, the word "algae" is still used in the names of some aquatic higher plants (such as Ceratophyllum, Kuroshio, Sargassum and Myriophyllum). ), may also come from this. On the contrary, people often call some small sticky green plants in water or on wet ground and walls moss. In fact, this is not moss now, but mainly algae. According to the modern understanding of algae plants, algae are not a natural taxonomic group, but they have the following characteristics:
1. Plants generally have no real differentiation of roots, stems and leaves. The morphological structure of algae plants is very inconsistent, and the size is also very different. For example, Chlorella, which is well known, is spherical and consists of single cells with a diameter of only a few microns; Macrocystis growing in the ocean has a complex structure, and its body length can reach more than 200 meters. Although the individual structure of algae plants varies in complexity and size, there is no real difference between roots, stems and leaves. Some macroalgae, such as marine kelp (kelp) and freshwater charophyta, can be divided into roots, stems and leaves in appearance, but they are not real roots, stems and leaves because they have no vascular system in their bodies. Therefore, algae plants are often referred to as phyllodes or protophytes.
2. Inorganic nutrition that can produce light energy Generally speaking, the cells of algae contain the same photosynthetic pigments as green higher plants, and some groups also have special pigments, and most of them are not green, so their plastids are called chromophores or chromophores. Algae can be nourished in various ways. For example, some lower unicellular algae can also be nourished by organic light energy, inorganic energy or organic energy under certain conditions. But most algae, like higher plants, can use carbon dioxide and water to synthesize organic matter under light conditions for inorganic photonutrition.
3. The reproductive organs are mostly composed of single cells. Sporangium that produces spores or sperm and egg storage devices that produce gametes in higher plants are generally composed of multiple cells. For example, mosses and ferns have a sterile cell wall outside the archegonium that produces eggs and sperm that produces sperm. But in algae, except for a few species, their reproductive organs are all composed of single cells.
4. The fertilized egg will not develop into an embryo in the mother. The zygote (fertilized egg) formed by the fusion of male and female gametes in higher plants develops into a multicellular embryo in the mother, and then continues to develop into a new individual without the mother. However, the fertilized eggs of algae do not develop into embryos in the mother, and only after leaving the mother can they divide and grow into new individuals. In zoology, higher plants are viviparous while algae are oviparous.
In a word, algae plants are a large class of plants that have no real root, stem and leaf differentiation, live a photoautotrophic life, and their reproductive organs are composed of single cells without embryonic development.
Fungi (fungi)
These groups include yeast, mold, toadstool and mold. They lack chlorophyll and have no structure of roots and leaves of organic plants. The evidence of their existence can be traced back to about 420 million years ago, but paleontologists think they should have appeared earlier.
Fungal plants, a large class of low-level plants that do not contain chlorophyll, cannot carry out photosynthesis and are heterotrophic. Include bacteria, slime molds and fungi. It is characterized by undifferentiated roots, stems and leaves, no photosynthetic pigments such as chlorophyll (except a few photosynthetic bacteria), no photosynthesis, no saprophytic or parasitic life, that is, heterotrophic life. The reproductive organs are mostly single-celled structures, and fertilized eggs do not develop into embryos.
Fungal plants live in a wide range of environments. They can survive in water, air, soil and even animals and plants.
Fungi are closely related to human beings, and many of them are edible or medicinal, such as making bread and wine with yeast, extracting drugs (such as penicillin) from mold, and edible fungi such as auricularia auricula and mushrooms. Many kinds have been widely used in industry and environmental protection to purify water. However, some fungi are very harmful to human beings, such as bringing diseases to people, animals and plants, making food and clothes rot and moldy.
It should also be pointed out that fungi play an extremely important role in the material cycle of nature. Thousands of creatures die every day in nature, as well as countless garbage and a lot of animal droppings. Then, over time, isn't the earth covered by biological "garbage"? Actually not, because there are many "cleaners" in nature. Bacteria and fungi do the best in this cleaning team. Their greatest skill is to break down dead complex creatures into simple inorganic substances. This process is not only a process of removing "garbage" in nature, but also a process of material circulation in nature. In short, without these cleaners, nature would really be covered with corpses. As a result, nitrogen, phosphorus, potassium, carbon and other elements can not be recovered, and the life of the whole biological world will end.
Fungi is a huge family, and it is everywhere. At present, there are about 654.38+million known fungi. Where do they live? What does it have to do with humans? How much can be used by humans? If we want fungi to enrich our life better, please join our big family of fungi and learn more about the fungi around us.
Lichen is a perennial plant, which is a composite organism composed of 1 fungi and 1 algae. Because the two plants have been closely combined for a long time, a single fixed organism of 1 has been formed in morphology, structure, physiology and heredity, which is the result of historical development. Therefore, lichens are regarded as 1 independent phylum. There are more than 500 genera and 25,000 species of plants in the world.
Most of the fungi that constitute lichens belong to ascomycetes and Sclerotinia, and a few belong to Basidiomycetes, Agaricus and Polyporales. There are also few people belonging to the subfamily Hemifungi. In addition, L species of water hyacinth have been found in Central Europe, belonging to algae.
The algae in lichens belong to more than 20 genera of green algae and cyanobacteria. Among the green algae, Tyebouxia, Trentepohlia and Nostoc commune of Cyanophyta account for about 90% of all lichen algae.
The hyphae in lichen are wrapped around algae cells and surround algae from the outside. Most of the organic matter produced by algae photosynthesis is captured by fungi, and algae are isolated from the external environment. They cannot absorb water, inorganic salts and carbon dioxide from the outside, so they have to rely on the supply of fungi. They are a special relationship of 1. Fungi control algae, and the shape of lichen is almost entirely determined by fungi.
Some people tried to take algae and fungi out of lichen and cultivate them separately, but algae grew vigorously and fungi starved to death. It can be seen that lichen fungi must rely on algae to survive.
Most lichens are plants that avoid light and need fresh air. Therefore, lichens can't be found in densely populated areas, especially near industrial cities. Lichens generally grow very slowly, only a few centimeters in a few years. Lichens can endure long-term drought, sleep during drought and grow after rain, so they can be born on cliffs, rocks, bark or desert land. Lichen is very cold-resistant, so other plants can't live in alpine zone, permafrost zone and polar regions, but lichen can grow and reproduce alone, often forming an endless lichen community.
Lichens, fungi and whole fungi are eukaryotes. In nature, lichens are often accompanied by bryophytes, so they are easily confused by people. In fact, bryophytes have primary differentiation of roots, stems and leaves and belong to higher green plants. Because it produces spores, it is called spore plant. Of course, ferns are also spore plants, but they are vascular spore plants, which are more advanced than non-vascular bryophytes in evolution. Lichens, on the other hand, have no real differentiation of roots, stems and leaves; It is not only more primitive than bryophytes in evolution, but more importantly, it is not a single plant organism, but a composite organism born of fungi and algae. Lichens are different from free-living fungi and free-living algae in morphology, anatomy, physiology, chemistry and distribution.
According to the external morphology, lichens can be divided into three categories: shell lichens, leaf lichens and dendritic lichens. Lichens crisscross, with dense and sparse colorless true hyphae, with algae layer in the middle, which is composed of algae cells. Bundles of false roots also extend from the lower layer, and there are no real organs such as roots, stems and leaves.
This fungus combines with algae in lichen, which makes it have amazing adaptability to the environment. The life materials needed for its growth mainly come from rain and dust, and it can adapt to extremely dry and barren environment. Among them, some hang on trees, revealing clusters of hair, such as taupe "litmus"; Some are fixed on bare rocks with different shapes, such as brightly colored "stone flowers". Lichen has become the dominant species of plants in the frozen Antarctic all the year round, with more than 400 species, including black, gray, yellow, white and red. It is really colorful, adding strange scenery to the Antarctic.
Lichens are not only beautiful, but also widely used. Litmus in lichen, clustered on the rock surface of Arctic tundra or in the snow and ice, is an important feed for reindeer in cold areas, so it is also called "reindeer moss".
There is a precious food in China and Japan-tremella, which grows on the precipice. Different kinds of lichens are the raw materials of native foods all over the world. For example, Icelanders eat lichen powder in bread, porridge or milk. France makes chocolate candy and chocolate powder from ground clothes. Some countries also use clothes to make wine.