Keeping Cut Flowers
While everybody enjoys fresh cut flowers around their house, few people know how
to keep them for as long as possible. This may be done by keeping in mind a few simple
facts.
An important thing to remember about cut flowers is that they are sensitive to
temperature. For example, studies have shown that cut carnations retain their
freshness eight times longer when kept at 12℃ than when kept at 26℃. Keeping
freshly harvested flowers at the right temperatures is probably the most important
aspect of flower care.
Flowers are not intended by nature to live very long. Their biological purpose is
simply to attract birds or insects, such as bees, for pollination. After that, they
quickly wither and die. The process by which flowers consume oxygen and emit carbon
dioxide, called respiration,generates the energy the flower needs to give the flower
its shape and colour. The making of seeds also depends on this energy. While all
living things respire, flowers have a high level of respiration. A result of all
this respiration is heat, and for flowers, the level of he at relative to the mass
of the flower is very high. Respiration also brings about the eventual death of the
flower, thus the greater the level of respiration, the sooner the flower dies.
How, then to control the rate at which flowers die? By controlling respiration.
How is respiration controlled? By controlling temperature. We know that respiration
produces heat, but the reverse is also true. Thus by maintaining low temperatures,
respiration is minimised and the cut flower will age more slowly. (Tropic
al flowers are an exception to this rule; they prefer warmer temperatures.)
Cooler temperatures also have the benefit of preserving the water content of the
flower, which helps to slow down ageing as well. This brings us to another important
aspect of cut flower care: humidity. The average air-conditioned room has a relative
humidity of 65%, which contributes to greater water loss in the flower. Flowers are
less likely to dry out if humidity levels are 90_95%, but this may be unrealistic
unless you live in the tropics or subtropics.
Yet another vital factor in keeping cut flowers is the quality of the water in which
they are placed. Flowers find it difficult to `drink' water that is dirty or otherwise
contaminated. Even when water looks and smells clean, it almost certainly contains
bacteria and fungi that can endanger the flowers. To rid the water of these unwanted
germs, household chlorine bleach can be used in small quantities. It is recommended
that 15 drops of chlorine bleach (at 4% solution )be added to each litre of water.
The water and solution should also be replaced each day.
When going to buy cut flowers, look for ones that have not been kept (by the flower
shop) in direct sunlight or strong wind. If the flowers are not freshly harvested,
ask whether they have been stored in a refrigerated coolroom.
1 The author of Keeping Cut Flowers believes flower care is dependent on
three main factors. one of them is temperature. What are the other TWO?
2 A DIFFERENCE OF 140C can extend the life of carnations by up to () times.
3 () and () are two aspects of a flower's appearance that depend on respiration.
KEY:1 humidity AND water quality(either order) 2 8/eight 3 shape AND colour(either order)
key:5 controlling temperature//maintaining low temperatures//cooler temperatures
6 water content 7 age(more)slowly 8 tropical
Wild Foods Of Australia
Over 120 years ago, the English botanist J.D.Hooker, writing of Australian edible
plants. suggested that many of them were `eatable but not worth eating'. Nevertheless,
the Australian flora, together with the fauna, supported the Aboriginal
people well before the arrival of Europeans. The Aborigines were not farmers an
d were wholly dependent for life on the wild products around them. They learned
to eat, often after treatment, a wide variety of plants.
The conquering Europeans displaced the Aborigines, killing many, driving others
from their traditional tribal lands. and eventually settling many of the tribal
remnants on government reserves, where flour and beef replaced nardoo and wallaby
as staple foods. And so, gradually, the vast store of knowledge, accumulated
over thousands of years, fell into disuse. Much was lost.
However, a few European men took an intelligent and even respectful interest in
the people who were being displaced. Explorers, missionaries, botanists,
naturalists and government officials observed, recorded and. fortunately in some
cases, published. Today, we can draw on these publications to form the main basis
of our knowledge of the edible, natural products of Australia. The picture is no
doubt mostly incomplete. We can only speculate on the number of edible plants on
which no observation was recorded.
Not all our information on the subject comes from the Aborigines. Times were hard
in the early days of European settlement, and traditional foods were often in
short supply or impossibly expensive for a pioneer trying to establish a farm in
the bush. And so necessity led to experimentation, just as it must have done for
the Aborigines, and experimentation led to some lucky results. So far as is known,
the Aborigines made no use of Leptospermum or Dodonaea as food plants,
Yet the early settlers found that one could be used as a substitute for tea and
the other for hops. These plants are not closely related to the species they replaced,
so their use was not based on botanical observation, Probably some experiments had
less happy endings; L.J.Webb has used the expression `eat, die and learn' in
connection with the Aboriginal experimentation, but it was the successful attempts
that became widely known. It is possible the edibility of some native plants used
by the Aborigines was discovered independently by the European settlers or their
descendants.
Explorers making long expeditions found it impossible to carry sufficient food for
the whole journey and were forced to rely, in part, on food that they could find
on the way, Still another source of information comes from the practice in other
countries. There are many species from northern Australia which occur also
in southeast Asia, where they are used for food.
In general, those Aborigines living in the dry inland areas were largely dependent
for their vegetable foods on seed such as those of grasses, acacias and eucalypts.
They ground these seeds between flat stones to make a coarse flour. Tribes
on the coast, and particularly those in the vicinity of coastal rainforests, had
a more varied vegetable diet with a higher proportion of fruits and tubers. Some
of the coastal plants, even if they had grown inland, probably would have been
unavailable as food since they required prolonged washing or soaking to render
them non-poisonous: many of the inland tribes could not obtain water in the
quantities necessary for such treatment. There was also considerable variation in
the edible plants available to Aborigines in different latitudes. In general, the
people who lived in the moist tropical areas enjoyed a much greater variety than
those in the southern part of Australia.
With all the hundreds of plant species used for food by the Australian
文章来源于网络，如有侵权请联系我们，将会在第一时间处理
更多资讯可以关注微信公众号：IELTSIM。
[AD] 点击此处了解【雅思合集】【学习计划定制】【终生VIP服务】
