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Plants

Plants: Overview
Plants are living organisms belonging to the kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The scientific study of plants, known as botany, has identified about 350,000 extant species of plants, defined as seed plants, bryophytes, ferns and fern allies. As of 2004, some 287,655 species had been identified, of which 258,650 are flowering and 18,000 bryophytes (see table below). Green plants, sometimes called Viridiplantae, obtain most of their energy from sunlight via a process called photosynthesis.
Importance of Plants To Mankind

The study of plant uses by people is termed economic botany or ethnobotany; some consider economic botany to focus on modern cultivated plants, while ethnobotany focuses on indigenous plants cultivated and used by native peoples. Human cultivation of plants is part of agriculture, which is the basis of human civilization. Plant agriculture is subdivided into agronomy, horticulture and forestry.

Food

Much of human nutrition depends on land plants, either directly or indirectly.
Human nutrition depends to a large extent on cereals, especially maize (or corn), wheat and rice. Other staple crops include potato, cassava, and legumes. Human food also includes vegetables, spices, and certain fruits, nuts, herbs, and edible flowers.
Beverages produced from plants include coffee, tea, wine, beer and alcohol. Sugar is obtained mainly from sugar cane and sugar beet.
Cooking oils and margarine come from maize, soybean, rapeseed, safflower, sunflower, olive and others.
Food additives include gum arabic, guar gum, locust bean gum, starch and pectin. Livestock animals including cows, pigs, sheep, and goats are all herbivores; and feed primarily or entirely on cereal plants, particularly grasses.

Non-food products

Wood is used for buildings, furniture, paper, cardboard, musical instruments and sports equipment. Cloth is often made from cotton, flax or synthetic fibers derived from cellulose, such as rayon and acetate. Renewable fuels from plants include firewood, peat and many other biofuels. Coal and petroleum are fossil fuels derived from plants. Medicines derived from plants include aspirin, taxol, morphine, quinine, reserpine, colchicine, digitalis and vincristine. There are hundreds of herbal supplements such as ginkgo, Echinacea, feverfew, and Saint John's wort. Pesticides derived from plants include nicotine, rotenone, strychnine and pyrethrins. Drugs obtained from plants include opium, cocaine and marijuana. Poisons from plants include ricin, hemlock and curare. Plants are the source of many natural products such as fibers, essential oils, dyes, pigments, waxes, tannins, latex, gums, resins, alkaloids, amber and cork. Products derived from plants include soaps, paints, shampoos, perfumes, cosmetics, turpentine, rubber, varnish, lubricants, linoleum, plastics, inks, chewing gum and hemp rope. Plants are also a primary source of basic chemicals for the industrial synthesis of a vast array of organic chemicals. These chemicals are used in a vast variety of studies and experiments.

Aesthetic uses

Thousands of plant species are cultivated for aesthetic purposes as well as to provide shade, modify temperatures, reduce wind, abate noise, provide privacy, and prevent soil erosion. People use cut flowers, dried flowers and houseplants indoors or in greenhouses. In outdoor gardens, lawn grasses, shade trees, ornamental trees, shrubs, vines, herbaceous perennials and bedding plants are used. Images of plants are often used in art, architecture, humor, language, and photography and on textiles, money, stamps, flags and coats of arms. Living plant art forms include topiary, bonsai, ikebana and espalier. Ornamental plants have sometimes changed the course of history, as in tulipomania. Plants are the basis of a multi-billion dollar per year tourism industry which includes travel to arboretums, botanical gardens, historic gardens, national parks, tulip festivals, rainforests, forests with colorful autumn leaves and the National Cherry Blossom Festival. Venus Flytrap, sensitive plant and resurrection plant are examples of plants sold as novelties.

Scientific and cultural uses

Tree rings are an important method of dating in archeology and serve as a record of past climates. Basic biological research has often been done with plants, such as the pea plants used to derive Gregor Mendel's laws of genetics. Space stations or space colonies may one day rely on plants for life support. Plants are used as national and state emblems, including state trees and state flowers. Ancient trees are revered and many are famous. Numerous world records are held by plants. Plants are often used as memorials, gifts and to mark special occasions such as births, deaths, weddings and holidays. Plants figure prominently in mythology, religion and literature. The field of ethnobotany studies plant use by indigenous cultures which helps to conserve endangered species as well as discover new medicinal plants. Gardening is the most popular leisure activity in the U.S. Working with plants or horticulture therapy is beneficial for rehabilitating people with disabilities. Certain plants contain psychotropic chemicals which are extracted and ingested, including tobacco, cannabis (marijuana), and opium.

Negative effects

Weeds are plants that grow where people do not want them. People have spread plants beyond their native ranges and some of these introduced plants become invasive, damaging existing ecosystems by displacing native species. Invasive plants cause billions of dollars in crop losses annually by displacing crop plants, they increase the cost of production and the use of chemical means to control them affects the environment.

Plants may cause harm to people and animals. Plants that produce windblown pollen invoke allergic reactions in people who suffer from hay fever. A wide variety of plants are poisonous to people and/or animals. Several plants cause skin irritations when touched, such as poison ivy. Certain plants contain psychotropic chemicals, which are extracted and ingested or smoked, including tobacco, cannabis (marijuana), cocaine and opium, causing damage to health or even death. Both illegal and legal drugs derived from plants have negative effects on the economy, affecting worker productivity and law enforcement costs. Some plants cause allergic reactions in people and animals when ingested, while other plants cause food intolerances that negatively affect health.

Plants With Health and Medicinal Values
ball1.gif (1653 bytes) Cancer-Fighting Foods
ball1.gif (1653 bytes) Exotic Fruits with health benefits
ball1.gif (1653 bytes) Plants that contain abundant antioxidants
ball1.gif (1653 bytes) High-Octane Foods
ball1.gif (1653 bytes) Spices: Healing Power
ball1.gif (1653 bytes) Tea: Health Benefits
Plants Vs Animals: How Plants and Animals Differ
Plants and animals are both kingdoms of living things. They differ in important aspects. The chart below summarizes some of these differences.
Plants
Animals
Plants generally are rooted in one place an do not move on their own Most animals have the ability to move fairly freely.
Plants contain chlorophyl and can make their own food

Animals cannot make their own food and are dependent on plants and other animals for food.

Plants give off oxygen and take in carbon dioxide given off by animals. Animals give off carbon dioxide which plants need to make food and take in oxygen which they need to breathe.
Plants cells have cell walls and other structures differ from those of animals. Animal cells do not have cell walls and have different structures than plant cells.
Plants have either no or very basic ability to sense. Animals have a much more highly develped sensory and nervous system.
Plant Species

Definition

The Plantae included several unrelated groups, and the fungi

Current definitions of Plantae

When the name Plantae or plants is applied to a specific taxon, it is usually referring to one of three concepts. From smallest to largest in inclusiveness, these three groupings are:


Name(s) Scope Description
Land plants, also known as Embryophyta or Metaphyta. Plantae sensu strictissimo As the narrowest of plant categories, this is further delineated below.
Green plants - also known as Viridiphyta or Chlorobionta Plantae sensu stricto Comprise the above Embryophytes, (i.e., primitive, and (i.e., such as sea lettuce. Viridiplantae encompasses a group of organisms that possess a and b, have that are bound by only two membranes, are capable of storing starch, and have in their. It is this which is mainly the subject of this article.
Archaeplastida, Plastida or Primoplantae Plantae sensu lato Comprises the green plants above, as well as (red algae) and (simple glaucophyte algae). As the broadest plant clade, this comprises most of the that eons ago acquired their directly by engulfing.

Outside of formal scientific contexts, the term "plant" implies an association with certain traits, such as multicellularity, cellulose, and photosynthesis. Many of the classification controversies involve organisms that are rarely encountered and are of minimal apparent economic significance, but are crucial in developing an understanding of the evolution of modern flora.

Algae

Most algae are no longer classified within the Kingdom Plantae. The algae comprise several different groups of organisms that produce energy through photosynthesis, each of which arose independently from separate non-photosynthetic ancestors. Most conspicuous among the algae are the seaweeds, multicellular algae that may roughly resemble terrestrial plants, but are classified among the green, red, and brown algae. Each of these algal groups also includes various microscopic and single-celled organisms.

The two groups of green algae are the closest relatives of land plants (embryophytes). The first of these groups is the Charophyta (desmids and stoneworts), from which the embryophytes developed. The sister group to the combined embryophytes and charophytes is the other group of green algae,Chlorophyta, and this more inclusive group is collectively referred to as the green plants or Viridiplantae. The Kingdom Plantae is often taken to mean this monophyletic grouping. With a few exceptions among the green algae, all such forms have cell walls containing cellulose, have chloroplasts containing chlorophylls a and b, and store food in the form of starch. They undergo closed mitosis without centrioles, and typically have mitochondria with flat cristae.

The chloroplasts of green plants are surrounded by two membranes, suggesting they originated directly from endosymbiotic cyanobacteria. The same is true of two additional groups of algae: the Rhodophyta (red algae) and Glaucophyta. All three groups together are generally believed to have a common origin, and so are classified together in the taxon Archaeplastida. In contrast, most other algae (e.g. heterokonts, haptophytes, dinoflagellates, and euglenids) have chloroplasts with three or four surrounding membranes. They are not close relatives of the green plants, presumably acquiring chloroplasts separately from ingested or symbiotic green and red algae.

Fungi

Fungi were previously included in the plant kingdom, but are now seen to be more closely related to animals. Unlike embryophytes and algae which are generally photosynthetic, fungi are often saprotrophs: obtaining food by breaking down and absorbing surrounding materials. Most fungi are formed by microscopic structures called hyphae, which may or may not be divided into cells but contain eukaryotic nuclei. Fruiting bodies, of which mushrooms are most familiar, are the reproductive structures of fungi. They are not related to any of the photosynthetic groups, but are close relatives of animals. Therefore, the fungi are in a kingdom of their own.

Diversity

About 350,000 species of plants, defined as seed plants, bryophytes, ferns and fern allies, are estimated to exist currently. As of 2004, some 287,655 species had been identified, of which 258,650 are flowering plants, 16,000 bryophytes, 11,000 ferns and 8,000 green algae.

Diversity of Living Plant Divisions
Informal Group Division Name Common Name No. of Living Species
Green algae Chlorophyta green algae (chlorophytes) 3,800
Charophyta green algae (desmids & charophytes) 4,000 - 6,000
Bryophytes Marchantiophyta liverworts 6,000 - 8,000
Anthocerotophyta hornworts 100 - 200
Bryophyta mosses 12,000
Pteridophytes Lycopodiophyta club mosses 1,200
Pteridophyta ferns, whisk ferns & horsetails 11,000
Seed plants Cycadophyta cycads 160
Ginkgophyta ginkgo 1
Pinophyta conifers 630
Gnetophyta gnetophytes 70
Magnoliophyta flowering plants 258,650
7 Most Poisonous Flowers in the World
Beautiful as they may be, some flowers are much more than they appear to be. Believe it or not, these seemingly harmless plants can really ruin your vacation. To help you know what flowers to stay away from on your trips, with a list of the worlds most attractive but dangerous flowers:

  • 1. Daphne
    Also known as lady laurel or paradise plant, Daphne is a 1-1.5 meters tall shrub, usually grown for its scented flowers. All parts of the plant are poisonous, but the greatest concentrations are in the sap and berries.

    Daphne contains mezerine and daphnin, two powerful toxins that cause stomach aches, headaches, diarrhoea, delirium and convulsions. If Daphne berries are consumed, the victim might fall into a coma and even die.

  • 2. Lily of the Valley
    Just like the Daphne, Lily of the Valley may look beautiful and harmless, but it is entirely poisonous. Eating one or two of the plants bell-shaped flowers won't hurt you very much, especially if you are an adult.

    Eaten in large quantities, Lily of the Valley causes pain in the mouth, nausea, vomiting, cramps and diarrhoea. People with heart conditions should be most careful since the toxins cause the heartbeats to slow down or become irregular.

  • 3. Belladonna
    Known as one of the most poisonous plants in the Western hemisphere, Belladonna contains potentially lethal tropane alkaloids. The entire plant is harmful, but its good-looking berries pose the most danger, especially to kids.

    The symptoms of Belladona, or Deadly Nightshade poisoning are dilated pupils, blurred vision, headaches, hallucinations, delirium and convulsions. Atropine, the toxin contained by Belladona, can kill a person by disrupting the nervous systems ability to regulate breathing, sweating and heart rate.

  • 4. Angels Trumpet
    Despite its name, there's something very evil about this plant. The toxins it contains can be fatal to humans and a number of animals. Known as a powerful hallucinogen, Angels Trumpet should not be used for recreational purposes, since the risk of an overdose is very high.

    Angels Trumpet plants contain a variable amount of tropane alkaloids, like atropine and scopolamine, and it is used in shamanic rituals by indigenous tribes in western Amazonia.

  • 5. Rhododendron
    This popular evergreen shrub, featuring large, beautiful blooms, has been known for its toxicity since ancient times. Xenophon recorded the odd behavior of a group of Greek soldiers who had eaten honey from rhododendron flowers.

    Rhododendron contains andromedatoxin which causes nausea, severe pains, paralysis and even death. Azaleas, members of the same plant-family as rhododendron, are also poisonous.

  • 6. Oleander
    Oleander is known as one of the most poisonous plants on Earth, often used in suicidal cases around southern India. The numerous toxic compounds contained in the entire Oleander plant, including oleandrin and neriine, affect the nervous, digestive and cardiovascular systems, all at the same time.

    Oleander poisoning leads to drowsiness, tremors, seizures, coma and even death. The plants sap causes skin irritation and severe eye inflammation.

  • 7. Autumn crocus
    One of the most endangered plants in the world, Autumn crocus is also probably the most poisonous. It contains colchicine, a deadly drug used effectively in the treatment for gout. Unlike other toxins found in the flowers above, colchicine, an arsenic-like poison has no antidote.

    Autumn crocus poisoning leads to reduced blood pressure and cardiac arrest.
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