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蕨类植物的理论研究

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蕨类植物的地理分布在种类的数量上及繁茂程度上主要是根据地球上各地的气候条件变化,特别是湿度和雨量变化而相应变化所决定的。其次,现代蕨类植物的分布格局是经历了漫长的地球历史的变而形成的。蕨类植物地理是蕨类植物现在和过去在空间上的关系,研究它的目的在于阐述蕨类植物在地球表面上分布的情况。蕨类植物的地理分布几乎是世界性的,除非洲的撒哈拉,地球的两极地和海拔较低的卡罗利来(Karoline)群岛中的少数岛屿无蕨类植物生长外,世界各地都存分布,它们不仅生活在热带和温带,而且也能生活于寒带,北到北纬83度的格陵兰,南到南纬55度的乔治岛和马克雷岛,分布最北部的种是冷蕨(Cysto. Pterlstragilis)和光岩蕨(Woodsia glabella);分布最南部的种是楯状膜蕨(Hymenaphyllum pe-lsatura)和羽状鸟毛蕨(Blechnum penna-mavia)。据目前统计,世界上大概分布着11,000种蕨类植物,它们以湿润的热带和亚热带为其分布中心,大约有10,000种(占总数的90%)分布在两个大的区域:一是美洲,包括墨西哥南部、由美洲、西委内瑞拉西部的安第斯,南到玻利维亚,另一个很大的分布区包括了我国南部、东南亚马来西亚、印度尼西亚和新几内亚及邻近的太平洋岛屿,非洲的热带和亚热带种类较少。研究表明,蕨类植物的地理分布类型可划分为世界广布型、热带分布型、温带分布型、间断分布型、特有分布型五大类。


1楼2012-11-14 10:21回复

    分布最为北的中 光岩蕨


    2楼2012-11-14 10:23
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      Blechnum penna-marina, alpine water fern or pinque (Chilean Spanish), is a species of fern in the family Blechnaceae, with a natural range from the Araucanía Region to the south and from the coast to the tree line of the Magellanic forests in Chile and adjacent areas of Argentina. It is also found in Australia and some Pacific islands. It is evergreen and grows to 20 cm (8 in).
      In cultivation this hardy species has gained the Royal Horticultural Society's Award of Garden Merit


      3楼2012-11-14 10:38
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        庐山石韦


        6楼2012-11-14 11:13
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          不错,谢谢lz


          IP属地:贵州来自Android客户端7楼2012-11-14 11:55
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            好贴啊


            来自手机贴吧10楼2012-11-14 21:01
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              被人们食用的种类有蕨、菜蕨、紫萁以及莲座蕨目的大部分种类。蕨类的根状茎富含淀粉,它的营养价值不亚于藕粉,不但可食,也可酿酒。
              华南紫萁

              紫萁

              蕨类的幼叶有特殊的清香美味,但在食前须先用米泔水或清水浸泡数日,除去其有毒成分,炒食或干制成蔬菜。食用和酿酒,桫椤茎干中含的胶质物也可食用。我国人民在北魏年间就开始食用蕨菜。目前随着人民生活水平的不断提高,追求食用无污染的山野菜尤其是被誉为山菜之王的蕨菜倍受人们的青睐。


              14楼2012-11-15 10:45
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                真美呀...闭上眼,已经感觉到它们的气息了..


                IP属地:贵州15楼2012-11-15 19:21
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                  Ferns are a very ancient family of plants: early fern fossils predate
                  the beginning of the Mesozoic era, 360 million years ago.
                  They are older than land animals and far older than the dinosaurs. They were thriving on Earth for two hundred million years before the flowering plants evolved.
                  As we know them now, most ferns are leafy plants that grow in moist areas under forest canopy. They are "vascular plants" with well-developed internal vein structures that promote the flow of water and nutrients. Unlike the other vascular plants, the flowering plants and conifers, where the adult plant grows immediately from the seed, ferns reproduce from spores and an intermediate plant stage called a gametophyte.What makes them different from other vascular plants?
                  There are two answers to this.
                  The first is that ferns are (relatively) delicate plants that only grow in areas where there are suitably moist conditions. They favour sheltered areas under the forest canopy, along creeks and streams and other sources of permanent moisture. They cannot grow readily in hot dry areas like flowering plants and conifers.
                  The second explanation ties in with the first: ferns reproduce differently from the conifers and flowering plants. It all has to do with moisture. Not just the moisture that allows the plant to live where it does, but the moisture that allows it to reproduce there.How do they reproduce?
                  As flowering plants are so common, we are all familiar with how they reproduce. It抯 useful to look at this first, to give us something to compare to ferns. Flowering plants (and conifers) reproduce when pollen from a male flower - carried by wind, insect or other vector - fertilises the female flower. (Many flowering plants, of course, include both male and female parts in the same flower). The male pollen cell carries half the genetic material of the adult plant and fuses its genetic material with that of the female cell, which carries the other half. The complete, fertilised cell grows into the seed, which, when ripe and when it finds itself in suitable soil and moisture, is capable of producing a complete adult plant.
                  Higher plants have a very robust propagation system: the pollen from the male flower is very hardy, and the female flower nurtures the seed until it is ready to grow. The seeds themselves are often very durable, able to wait for long periods in adverse conditions before they grow. So the higher vascular plants have evolved to occupy nearly every niche on the land surface of the earth.
                  Ferns do it differently. They have a more complicated method that depends on there being liquid water for the process to complete. As a result, they can only reproduce where there is sufficient moisture: the reproduction process itself requires moisture.
                  So, how do they do it? To detail this, I need to describe some of the parts of a fern.
                  Parts of the fern - and some names for them
                  The leafy branch of the fern is usually called a frond. The small leaflets that make up the whole frond are called pinnae.


                  17楼2012-11-28 11:03
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                    If you look underneath a fern frond, you will often see small clumps, spots or patches that look like they are stuck onto the under surface of the pinnae. These patches are where you find the spores. The spores
                    grow inside casings called sporangia. The sporangia may clump together into what are called sori (singular: sorus). Photo (A) below shows sporangia clumped into sori on a Kangaroo Fern frond. Sometimes these sori follow the fern leaf veins, sometimes they are set into indentations in the underside of the pinna. Not every frond has spores under it: fronds that have the spores are called fertile fronds.
                    Take a look more closely at the spore structures under the pinnae of a fertile frond, using a hand lens. In some cases, you will see that each is composed of myriads of smaller structures. These are the sporangia - the spore casings that hold the spores. Some ferns protect their sporangia with thin semi-transparent membranes, often globular in shape, called indusia. Inside the indusium (if there is one) there are the sporangia. Photo (B) below shows open indusia on a Soft Tree Fern frond.
                    Other ferns don't have the indusium, the sporangia are open to the outside world. The sporangia are usually tiny - maybe half a millimetre (one fiftieth of an inch) across. The spores of course are even smaller.
                    Sometimes the sporangia are tucked under a curled-over part of the margin of the pinna. Photo (C) shows this effect on the underside of a Maidenhair Fern.

                    If you take a piece of mature fertile fern frond and place it face up inside a book - or on a piece of paper under a weight - so that the spore material is on the underneath of the frond , then leave it overnight, you抮e likely to find the next day that the spores have been released as a fine coloured powder onto the paper. They show up as a fine pattern tracing the form of the fern frond. They can be black, brown, reddish, yellow or even green, but they are extremely small. Each of these spores is capable - through a circuitous process - of growing into an adult fern.How do the spores grow?
                    If the spore finds suitable conditions, it will grow into a tiny heart-shaped plantlet called a prothallus or gametophyte. In this regard, the spore behaves quite like the seed of a higher plant, except that what grows from the seed is the full adult plant, but what grows from the spore is the gametophyte. The gametophyte is not the full fern, but a plant with only half the genetic material of the adult fern, rather like a sperm cell or an egg cell. The gametophyte is the intermediate stage from spore to adult fern.
                    If the gametophyte finds itself in a suitably moist place, fertilisation takes place, and it is transformed into a complete adult plant. It becomes what抯 called a sporophyte. Given the right conditions, this tiny sporophyte will continue to grow into a full adult fern, where it can produce spores of its own, to repeat the life cycle.


                    18楼2012-11-28 11:03
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                      This is how it works, in more detail:
                      What happens with a gametophyte can only be seen under a strong lens, as the gametophyte is small - usually less that half an inch across. The gametophyte has two sets of reproductive organs on its underside - the male parts called the antheridia, and the female parts called the archegonia. The antheridium contains sperm cells while the archegonium contains egg cells. They are each located on the gametophyte, a little separated from each other. If there is a film of moisture, the sperm cells from the antheridium swim towards the egg cells in the archegonium. This may be on the same gametophyte or an adjacent one.
                      When the sperm cells find the egg cells, they fuse their genetic material to make a cell with the full adult fern set of genes. This cell is the beginning of the adult fern, located in and protected by the gametophyte structure. As it grows to become the sporophyte, it takes over from the gametophyte and becomes the adult fern.
                      Here is a diagram that shows the fern life cycle.

                      The diagram is adapted from a more detailed one on the Australian National Botanic Gardens website.
                      Ferns can reproduce in other ways, too. It is possible for a sporophyte to grow from the gametophyte without fertilisation, a process known as apogamy. This can happen in drier areas where there is insufficient water to allow normal fertilisation. Ferns can also grow from spreading rhizomes (roots) of existing plants. Brackens often spread this way. Or they can sprout baby ferns at the "proliferous" tips of their fronds. When the parent frond droops and touches the soil, the baby plant takes root on its own. Photo (D) shows a proliferous tip on a Mother Spleenwort fern. It is a faster method that some ferns use to reproduce mature adult plants, in addition to normal reproduction by spores.
                      Of course, the proliferous baby plant, or the frond that grows from the spreading rhizome, is identical genetically with the plant it sprang from. Only ferns that grow from spores using normal fertilisation can take advantage of the genetic diversity offered by the full reproduction process.What affects where ferns will grow?
                      There are several factors that adult ferns need to survive (ignoring pests or disease):moisture in the soil; moisture in the air; suitable nutrients in the soil; sufficient light for photosynthesis; suitable temperatures; protection from wind; protection from too much sunlight; protection from freezing; and dependability and continuity of the previous requirements.
                      Depending on the type of fern, the degree of each factor required can vary greatly.
                      Another factor that is less often recognised is the difference between the conditions needed for a fern to survive, and the conditions it needs to reproduce. A fern may live quite happily in a relatively hostile environment, but it may not reproduce there. You will only find ferns growing naturally in areas where, at least for some of the time, the conditions suit both survival of the adult plant and reproduction � which means the survival of the gametophyte. Perhaps more than any other factor, it may be the hardiness of the gametophytes that determines whether a fern will thrive naturally in an area or not.Why do ferns grow in some places and not others, and why do some species thrive where others don't?
                      Like all plants, ferns have evolved to suit their environment. Some can tolerate extreme drought and heat, others only live in the deepest rainforest. You can grow a cactus in the sub-Antarctic, though grasses will survive there. And likewise, you can抰 expect a tree fern to grow in a desert, though some varieties of rock fern do.
                      Ferns are very successful niche plants: they are well adapted to particular environmental niches - soil moisture, humidity, light, etc. They seldom grow outside these niches, some of which are very specific. For example, in our region, the Mother Spleenwort fern always grows near waterfalls.


                      19楼2012-11-28 11:03
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                        都怪从前没好好读书,只识中文.悲哀............


                        IP属地:贵州20楼2012-11-30 19:18
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                          蕨类的叶脉类型


                          21楼2013-04-09 00:13
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                            22楼2013-04-13 16:02
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                              23楼2013-11-08 17:47
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