第1个回答 2020-08-04
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If you want to ask what animal is the most intelligent, the answer should be human, because human beings know that things are for me. So what's the smartest plant? If you look at it from the perspective of using things for me, there's no doubt that orchids are the smartest plants in the world. During the process of seed germination, growth and flowering and fruiting, orchids need to use other organisms to help complete the life cycle of orchids.
Orchid seed has its own distinctive characteristics in plants, mainly in the following aspects.
First, the number is huge and uneven. One capsule of orchid (commonly known as POD) can have up to 4 million seeds, but the minimum is only 20-50 seeds, with a difference of 80000-200000 times.
Second, the seeds are very small. The seeds are generally 0.05-6 mm long and 0.01 to 0.9 mm wide (the diameter of a hair is generally 0.08 mm).
3. The seed structure is simple. The outer testa of orchid seeds accounts for most of them, but the embryo is very small. Generally, the size of embryo is only about 1110 of the seed size. The smallest embryo is 0.1 mm long and only 0.078 mm wide (equivalent to the diameter of a hair). The embryo of orchid seed has no cotyledon or endosperm, that is to say, the mother plant of orchid does not provide any substance to help its offspring (seed) germinate and grow early.
4. There are many air filled cavities in the outer seed coat of orchid seeds, so the orchid seeds are very light. The heaviest orchid seeds are only 14-17 centigrams (1 centigram is equal to 1 / 100 grams), and the lightest ones are only 0.3-0.4 centigrams. Such a light seed can float far away from the mother plant with the help of wind and settle down. At the same time, there is a layer of closely arranged cells on the surface of the seed coat of orchid, so that the water is not easy to penetrate into the seed quickly, so that the orchid seed can float on the water surface and float for a long distance. Of course, orchid seeds can also be spread by animals, such as adhering to animal fur or claws covered with mud, or feathers of birds. They can also be spread by animal feeding, and even by human activities. For example, a kind of fire orchid distributed in North America was spread from Europe to North America through human activities. The plants of Cymbidium spp. can only be seen on the surface of the earth, such as the plants of Orchidaceae, which are very high in calcium content, and can not be seen on the surface of the earth. We found more than 30 kinds of terrestrial orchids in a gully about 2.5 km long and 0.5 km wide in Huanglong scenic area of Sichuan Province, and tens of thousands of orchids grew together. Huanglonggou is a tuffaceous gully that gradually rises from south to north. It is the unique travertine in the gully that provides suitable habitat for the growth of orchids and forms a completely different vegetation type with orchids as the main body from the adjacent gullies. Orchid seeds do not have any stored nutrients to help them germinate and grow. When orchid seeds germinate and grow together with the seeds of other plants with cotyledons or endosperm in the same lifetime, it is obvious that orchid seeds belong to the "vulnerable group", and their germination and seedling growth after germination cannot compete with other plants, because plants with cotyledons or endosperm germinate in seeds The stage and seedling stage can survive this critical and difficult period with the help of nutrients stored in cotyledons or endosperm. This is the main reason why orchids always grow in special habitats where other plants are difficult to grow. So how does orchid seed germinate and grow in these special habitats? The secret is that orchid seeds use fungi to help it absorb nutrients and water during germination and growth. It has been found that orchid seeds must be assisted by fungi when they germinate under natural conditions. Some orchid species need fungi to help them absorb nutrients and water during the whole development process from seed germination to seedling, growth and mature plants, which is the case for saprophytic orchids without chlorophyll. If there is an orchid in Australia that grows under the earth's surface all its life, there must be fungi to help it absorb nutrients and complete its life cycle. Even some species need different kinds of fungi to help at different stages of growth and development. The most typical example is Gastrodia elata, a famous medicinal plant. Through nearly 30 years of research, Chinese scientists first found that Gastrodia elata seeds need to use fungi called small mushrooms to help them obtain nutrition and germinate. After the germinated seedlings (protocorms) grow other propagation bulbs, they need to cooperate with a fungus called Armillaria mellea to help them grow and develop. Some orchid species do not need the help of fungi after the seedling growth stage, but fungi still exist in the roots and even stems of these orchids. Some of these fungi are beneficial to the orchid, while others are not. Therefore, in the critical and difficult period of germination and seedling growth, tiny orchid seeds skillfully rely on the help of fungi to survive in places where other plants are difficult to survive.
In the process from seed to seedling, orchid adopts a strategy of wide planting and thin harvest, which produces a large number of seeds, but only a few seeds can germinate, grow and finally grow into mature plants. However, in the process from flowering to fruiting, a completely different strategy was adopted. orchid