Plants are multicellular, mostly photosynthetic eukaryotes that also have cell walls composed of cellulose, do not have a central nervous system, are generally non-motile, and reproduce sexually, often by alternation of phases of a single generation (Alternation of generations). This kingdom includes familiar organisms such as trees, shrubs, herbs, and ferns.
In 2011, a study was published that estimated the number of plant species on the planet at about 8.7 million, of which 6.5 million species were on land and 2.2 million species in the sea. By 2004, the number of plant species that were distinguished and identified reached 287,655 plant species, of which 258,650 are flowering and 15, 000 anaerovascular.
In addition to plants’ central ecological role—photosynthesis and carbon fixation by plants is the ultimate source of energy and organic material for nearly all ecosystems, and plants are primary producers of atmospheric oxygen—plants provide to humans vital nutritional and economic values. Indeed, the human diet is centered on plants, whether directly via grains, fruits, vegetables, legumes, and so forth, or indirectly via animals that consume or pollinate plants. Plants also provide valuable products, such as lumber, paper, and medicines. Beyond these external values, plants also touch upon the inner nature of people by providing aesthetic value and joy, such as their use in landscaping, decoration, and works of art, as well as via the smells and sights of flowers and the rich tastes of fruits.
Features of plants.
1. They are living creatures with real kernels.
2. Their bodies are multicellular.
3. They photosynthesize because they contain chloroplasts that contain chlorophyll.
4. Her cells have cell walls made of cellulose.
5. Often immobile (virtual movement).
6. They live in different environments on land, fresh and salt water.
Plants are divided into:
▪️ seed plants.
The seed plants are the finest and most abundant plants on the surface of the earth. It is believed that they originated and evolved from terridium plants that form two types of heterosporous germs similar to cellaginella or from the extinct seed ferns. Evolution depended on the reduction of the gametophyte phase and its formation within the body of the bacterial plant.
Seed-bearing plants are conventionally divided into seed envelopes (or flowering plants), and gymnosperms that include gentoids, cycads (Latin: cycadophyta), ginkgoids (Latin: ginkgo), and finally conifers.
Angiosperms are currently thought to have evolved from the ancestors of gymnosperms, making the classification of gymnosperms semi-racial.
▪️ It is widely spread as it grows in temperate, tropical and cold regions.
▪️ They contain cones that hold seeds instead of flowers. These seeds are bare over the surfaces of the krappel (scales) of the cones, which is why they are called gymnosperms.
2. Angiosperms (flowering plants).
▪️ This class is characterized by the presence of the sexual reproductive organ, the flower.
▪️ These plants are found in all habitats on Earth’s surface.
▪️ The seeds are formed inside the crayfish of the female flowers and are therefore called angiosperms (covered) seeds.
▪️ avascular plants.
They are terrestrial plants such as green algae that do not have vessels that carry raw and deficient sap, unlike vascular plants. And vascular plants, even if they are tissueless, some of their species have tissues that carry water inside them. The avascular plants have neither roots nor leaves, the roots and leaves are called so if they contain vessels inside them and the avascular plants are not as well. The lobes (round pieces) on them look like leaves and not, because they don’t have bark. They are non-flowering and seedless plants that reproduce by spores.
Avascular plants are a biological branch traditionally used to refer to all embryonic plants (scientific name: embryophytes) that do not contain true vascular tissue and therefore are called “avascular plants”. Some vascular plants do contain specialized tissues for carrying water, but since those tissues do not contain lignans, they cannot be considered true vascular tissues.
It is now believed that vascular plants are not a natural or monophyletic group, yet this name is appropriate and remains in use as a collective term referring to mosses, hornworts and hepatic plants. Avascular plants produce encapsulated reproductive structures (gametes and spores), but they do not produce flowers or seeds that spawn through the sporophytes.
It is a botanical genus that belongs to the fern family.
It is a botanical order that follows the ferns of the ferns of the Eukaryotes Division. They are non-flowering plants that include long, green and lobed leaves. They grow in areas where moisture is available. They can reach a height of up to 30 meters in tropical regions.
The ferns appeared in the early period exactly in the Devonian era, and they spread in abundance during the Carboniferous period of the same era.
During the period of reproduction, the leaves of the plant grow spore sacs containing spores, which fall to the ground and germinate, indicating that it has two male and female reproductive systems (bisexual) that produce gametes, then after fertilization an embryo is formed that enters into hibernation waiting for the appropriate germination conditions.
The underside of some fern leaves contains shrubs or yellow clusters that are spore sacs and play an essential role in the reproduction process. When the sporophyte matures, it bursts and releases spores. Each spore grows in a medium where adequate moisture and temperature are available. It ends with the transformation into a heart-shaped gametophyte called the gametophyte.
After the ripening process, the moleifera produces gametes that are transferred swimming on a layer of water, to reach the oviducts, where fertilization takes place, and the egg cell that undergoes divisions is formed to form a new fern, which first grows at the expense of the marshal, where lunch is derived from it and leaves appear to it while it is wrapped And then spirally strikes it in the soil to absorb its lunch, which consists of water and mineral salts.
It is a heterogeneous group of seedless vascular plants.
Plant parts and their functions. Each of the many plants on our planet, including trees, shrubs, herbs, ferns, vines, and mosses, have parts.
What are the parts of a plant.
The parts of flowering plants that are the most common plants on Earth are:
1. The root, is the part of the soil that grows in most types of plants.
▪️ Root functions.
1- It fixes the plant in the soil.
2- It absorbs water and dissolved salt in the soil.
3- It stores food just like it does in sweet potato root, which stores food.
2. The stem, is the part that supports the plant.
▪️ Leg functions.
1- The stem helps carry the plant, its leaves and buds, and thus support it.
2- The stem helps transport both salt and water from the root to the leaves, and it also transfers food that has been photosynthesized from the leaves to other parts of the plant.
3- The stem helps in storing food, and from the plants whose stalk is able to store food / vines, tubers, rhizomes, and others.
4- It helps in the manufacture of food, as some types of plants in which the green leg manufactures food.
3. The leaves, which is the part that consists of the leaf of the plant in which the veins are located, through which the water and food for the plant pass, and also made up of the neck, whose task is to tie the leaf itself to the stem.
▪️ Leaves functions.
1- The main function of paper is to manufacture food through the process of photosynthesis.
2- Plants manufacture food through the chloroplasts they contain, and these plastids contain the chlorophyll pigment, and the photosynthesis process has several stages that they do, which are:
– The chlorophyll pigment in the paper absorbs sunlight.
– Sunlight and the enzymes present in the paper analyze water for its basic elements, hydrogen and oxygen.
– The oxygen is released from the pores in the leaves, and it helps to increase the oxygen stores in the atmosphere.
– The remaining hydrogen combines with carbon dioxide by means of enzymes, and forms sugars on which plants and animals feed.
4. Flowers and this part also consists of several parts, they are:
– The sepal, which is the green leaves that surround the flower, and its role is to protect the inner parts of it, and the sepal group is called the calyx or the calyx.
– Petals, which are colorful floral leaves, which often have a scent, and their mission is to attract insects.
– Stamen, which is the male organ in the flower and its mission is to produce pollen, and it consists of filament or filament and anther.
– The carpel or carpel, which is the female organ in the flower, and it consists of the ovary or ovary and the pen or style and the stigma that receives the pollen.
▪️ Flowers functions.
1- The flower is the part responsible for the sexual reproduction process by plants, and the flower is made up of parts, the parts that enter into the sexual reproduction process in the flower are:
▪️the anthers or the male organ that produces pollen and the anthers are in the pouch, the ovary or the female organ that is found in the carpel Its role is to produce the ovum, and the petals release a scent that attracts insects and birds, which contribute to the transfer of pollen grains from the anthers to the ovaries, and this results in the fertilization of the egg.
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