Cycads
Cycads are what we often call iron trees,
Why is it called the Iron Tree?
There are generally two theories.
The first is that cycad wood is dense
, put it in the water, it will sink as quickly as iron;
The second is that cycads need a lot of iron during their growth.
Cycads called “iron trees”
Although these two statements are not supported by science at present, they still have a certain degree of credibility based on people’s long-term cultivation experience.
Cycads, also known as anchovy plantains, fire-sheltered plantains, phoenix pines, etc., are now distributed in Fujian, Taiwan, Guangdong in China, and also distributed in Japan, the Philippines and Indonesia
。
The biggest feature of cycads is that they bloom in a certain period.
Fork leaf cycad hand drawing
The iron tree blooms
Now we often use “iron tree blossom” to describe something that is very rare or difficult to complete, and the iron tree here refers to
。 The “blossom” here does not really mean that cycads bloom,
Rather, it means that the iron tree receives pollen transmitted by other cycads, thus completing the process of racial continuation between plants.
“Cycad Blossom”
Adult cycads bloom almost every year, and the flowers of female and male plants are completely different.
The flowers of both the female and male cycads are located in the very center of the plant and are both golden yellow.
But the female plant has bulbous flowers, while the male plant is cob-shaped like corn on the cob
。 It is precisely because the state of cycad blooming is far from other flowers,
So even if it blooms, it is difficult for people to recognize it as its flower.
Female and male strains of cycads
Moreover, cycads have different flowering and fruiting times in different places. In tropical and sub-hot regions of China,
Cycads that are more than 10 years old basically bloom and bear fruit every year.
However, cycads cultivated in the Yangtze River Basin and northern regions are difficult to bear fruit for almost a lifetime, and more often,
Occasionally it blooms once and bears fruit once.
Reproduction of cycads
In nature, plants do not continue the survival of the race through mating like animals, usually through the spread and combination of pollen to complete the reproduction between plants.
Plants are generally divided into dioecious and dioecious plants.
Hermaphrodites can reproduce on their own, while dioecious plants usually need to release mating information by flowering
, and through this to complete a new round of reproduction, this is called
sexual reproduction
Sexual reproduction of plants
It’s typical
dioecism
Plants need pollen transmission to reproduce, which dooms a cycad to be unable to complete the continuation of the race
。 In the past, cycads were transmitted by pollen to continue genes.
Since cycads themselves cannot move, pollination can only be completed with the help of wind and insects.
Dioecious, dioecious
So cycads in the wild want to multiply,
It is necessary to ensure that there are suitable numbers of xenomorphs in a certain area.
This requirement seems very demanding now, but in the Jurassic era this link is easier than everyone thinks, after all, cycads can be found everywhere.
Cycads in history
Here you may have such doubts, iron trees are not everywhere,
There are also many iron trees cultivated in flower shops all over the world, and it is quite easy to breed.
But we first have to understand one thing.
It is a large range that refers to cycads in the cycad family
。 Not every type of cycad can be potted, and some of these species are on the verge of extinction.
Cycads are an ancient plant, gymnosperms from the early Earth, dating back to the earliest
Permian period
And reached its peak during the Jurassic to Cretaceous period. During this period, its existence could be seen in every corner of the world, one-fifth of all plants at that time.
This period is also known by scientists as the “Cycad Age”.
Cycads, so to speak, not only experienced
Permian mass extinction
, It has also withstood many changes in the earth’s climate and environment such as the Cretaceous mass extinction and the fourth season glacier, and is a rather remarkable plant,
It is a first-class protected plant in China.
Wood Cycad
At present, the cycads that can be seen everywhere are artificially cultivated,
Wild cycads are quite small and have long been listed as critically endangered.
thereinto
It has been listed as extinct species in the wild.
The loneliest plant in the world – the wood cycad
The wood cycad is what we mentioned in the title already
Single tree for 127 years.
Famous botanist in 1895
John Medley Wood
, I saw a beautiful tree in South Africa, it resembled a palm tree.
And like palm trees, they have thick green leaves, but their leaves are drooping, which looks like an umbrella-shaped crown from a distance. The leaves are surrounded by an orange-yellow corolla, which looks very beautiful.
Wood sent the bud of the tree to London and named it Wood Cycad.
The loneliest tree: the wood cycad
Due to the extremely high medicinal value of wood cycads, local residents in South Africa take full advantage of this and use cycads in large quantities. meanwhile
Due to changes in the natural environment, plus
The high demands placed on the habitat further accelerate its demise.
Slowly, South African locals are discovering that it is becoming increasingly difficult to see wild wood cycads in the wild. This continued until 1916,
The world’s last recognized wild wood cycad was found on the edge of the Noye Forest in South Africa.
In order to protect the world’s last wood cycad, experts carefully transplanted it into a botanical garden and cared for it with care.
Protect the Wood Iron Tree
Transplanting it to the Botanical Garden is not only for conservation reasons, but also to continue the Wood cycad race through human intervention.
Botanists are destined to be disappointed because the Woodiron tree is the last male in the world, and no female plant has been found that could help pollinate it.
You know,
The lifespan of wood cycads is very long, around 200 years
。 But the last one
Male strain
Even with the help of scientists, no female strain has been found that can bind to its genes.
Cycad male strain
Now this is the only tree in the world, which should bloom every year, waiting for the breeze to bring female pollen to complete the continuation, but its flowering frequency is decreasing year by year.
After 127 years of waiting for a partner alone, it seems to have resigned itself.
asexual reproduction
Also known as gametophyte reproduction, it refers to a method of reproduction that does not produce offspring through sex cells.
Asexual reproduction is usually common in single-cell and low-grade multicellular.
Because it is not inherited by a single parent through sex cells, it does not have a complex embryonic development process, let alone genetic recombination.
Therefore, the offspring genes of asexual reproduction are exactly the same as the parent genes.
Asexual reproduction produces offspring by splitting and budding.
The Woodiron tree reproduces autonomously
There are still a lot of wood cycads in existence, but why it is said that it is the last wood cycad in the world, this is because they are all sprouted through the main plant.
There is basically no difference in genes, and it can be seen as a whole, which is Wood Cycad
Now this male plant has cloned a large number of “descendants”,
There is little difference in their genes.
Everyone should know that this kind of self-reproduction does expand the population in the short term, but in the long run it is completely detrimental to the continuation of the race.
Because of such monomer replication, led to the wood cycad
gene
Single, insufficient diversity, such genes are lacking the ability to resist external changes.
Maybe someday in the future,
The wood cycad will become extinct due to sudden changes in the environment, completely disappearing from the earth.
Salvation of scientists
In order to save the wood cycad, which has been lonely for 127 years, from singleness, scientists came up with such a plan,
That is to find the close relatives of the wood cycad, and then crossbreed and backcross, will
Keep purifying, and then get a new Pin Wood Cycad.
It’s not a wood cycad in the true sense of the word, but it’s infinitely close to it.
Mimic genes
During the implementation of the program,
Although the scientists found a close relative of the wood cycad (Netal cycad), they also crossed and bred the female strain they planned.
But the results were extremely disappointing, because this hybrid produced offspring on the female plant
The proportion of wood cycad genes is very small
especially
chloroplast
on genes, almost negligible.
No matter how many times it is backcrossed with such a new variety of cycad, the genes in its offspring will be significantly biased towards Netal cycads.
In this way, the hybrid purification program failed, and the wood cycad continued to remain single.
Waiting wood cycads
In fact, for this wood cycad, time is not a problem, it is in the period of the strongest vitality, usually there will be people to take care of it, waiting for seventy or eighty years is no problem at all.
But now the environmental climate is very unstable and changing all the time, this pair
That’s very bad news because it’s so genetically single.
Unless a female Wood cycad is found before the end of its life, it will continue to be alone for 127 years.
Not surprisingly, he will carry this loneliness to extinction, which also means that the wood cycad disappears from the earth forever.
Cycads
Cycads
Cycads
Cycads
Cycads
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Wood Cycad
Wood Cycad
Wood Cycad
asexual reproduction
asexual reproduction
gene
chloroplast
