Medical Plants (реферат)

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The plant kingdom is rich and varied. There are some 500,000 different
species of plants. Plants have different “natural homes” (habitats).
Cultivated plants from the garden differ greatly from the plants growing
in the field or in the meadow. Some plants are familiar to you. You
feast your eyes on modest bell-flowers, timid violets, bright poppies,
luxuriant roses, fragrant lilac, long clusters of showy coloured flowers
of hollyhock and evergreen leaves of ivy.

Don’t gather meadow and field flowers into bouquets. Some of them are
rare species. Many plants produce poison that can kill or sicken people
that come in contact with the plant. Touching poison ivy (a shrubby or
climbing plant that has small, greenish berries and leaflets in groups
of three) causes a severe, itching skin rash; eating certain holly
berries (a shrub or a tree having evergreen leaves with pricky edges and
bright-red berries) causes vomiting; chewing a stem of hemlock (a
poisonous plant with featherlike leaves and flat clusters of small
whitish flowers) can kill an adult.

The best rule for dealing with plants is: never eat or chew any wild

But some of the chemical plants are used to produce medicines that ease
human suffering and cure serious illnesses. Medical plants and some
poisonous ones serve as a raw material for medicines.

A plant with a slender cluster of fragrant bell-shaped white flowers is
called lily of the valley. It is a raw material for extracts to cure
heart diseases. A bitter medical drug made from the dried juice of aloe
(a tropical plant with thick, spiny-toothed leaves) is used to stimulate
the digestive tract. The juice extracted from fresh leaves is used for
applications on fester wounds and abscesses.

A North American shrub with yellow flowers that bloom in late autumn or
winter is called witch hazel. A spicy-smeliing liquid made from the bark
and leaves of this plant and rubbed on the skin relieves an open injury
or wound pain. Early Native Americans were good at using various herbs
and plants for medical purposes. The Hurons had a cure from scurvy (a
disease caused by lack of fresh fruit and vegetables). They made a tonic
from the bark and needles of an ever green tree that carried massive
dozes of vitamin C. The Incas used a colourless substance from certain
cinchona (a South American tree) barks to cure malaria. Bitter drugs or
chemicals derived from quinine are used to treat malaria nowadays.

Over 200 years ago, doctors prepared medicines from the bark of willow
trees. The bark contains a chemical that can ease or reduce fevers. The
willow bark contains salicylate, an active ingredient of aspirin.

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