Data and characteristics of trees
I will introduce you to the information and characteristics of the tree and the green plant maintenance experience that explains the detailed introduction of the tree. The following is a detailed introduction. If we have to describe it, we may think that the tree is very long-lived, woody, and very tall... The life span of many plants is predictable, and they follow what scientists call "programmatic aging." But trees are not. Many trees can survive for hundreds of years. In fact, the characteristic of indefinite growth may be the most accurate scientific definition of a tree, even exceeding the characteristic of woody. But this can only help us determine what a tree is to a certain extent.
Although we think we know what a tree is, when we try to define it clearly, all the words slip out of our heads... 1. Long-lived trees cannot be grouped into a clear group, they have multiple genealogy, and over the long evolutionary history, multiple strategies have been adopted to grow into what they are today. Take the longevity of trees for example. A classic example is a 5067-year-old fox-tailed pine tree growing in the White Mountains of California. This tall tree holds the current longevity record. When the first pyramid in ancient Egypt was built, the tree was already about 500 years old. Scientists speculate that the reason why the strong foxtail pines are so durable is largely due to their geographical location: they have avoided fires that sweep across low-altitude areas; pests are also far away from them because they cannot endure the harsh terrain of the subalpine belt.
Not far below the altitude where the foxtail pine stands, huge sequoias grow. These giant trunks can be more than 10 meters wide. They can also survive for thousands of years, but adopt a very different approach to longevity: using thick, corrosion-resistant bark and large amounts of repellent compounds inside to ward off fires and pests.
About 650 kilometers further east, a slender tree that lives longer than the giant foxtail pine and sequoias grows, the fluttering poplar, but they adopt a different strategy. Shaking poplar is a tree that you can easily hug. Their height is rarely more than 15 meters. In addition, they are also good at growing new shoots from the bottom of trees, forming huge "tree clusters" when in fact they are made up of individuals with the same genes connected to each other underground. In Utah, the United States, there is a community of trembling poplar trees that has a history of about 80,000 years. At that time, Neanderthals were still thriving on the earth.
2. Shrubs also live long. Once asexual reproduction is added, trees will soon lose their dominant position in the longevity world. King's Mountain longan is native to Tasmania, Australia and is a shining green shrub. To be precise, shrubs are not trees because they do not have a central main stem. There is only one species of Jinshishan longan in the world. Although they bloom occasionally, no one has ever seen their fruits, so scientists believe they reproduce completely asexually. According to recent radiocarbon dating, Jinshi Mountain longan is at least 43000 years old.
In addition, in the Mojave Desert in California, there is a carbolic bush called the "Clone King". Their age is estimated to be 11700 years old. From this point of view, longevity is not satisfactory to find a unified characteristic that determines what makes a tree a tree.
3. Tree woody characteristics Andrew Groover, a geneticist at the U.S. Forest Service's Pacific Southwest Research Station, spent a lot of time studying trees and quickly realized that the definition of a tree was problematic. In a 2015 article published in Trends in Plant Science, Groover wrote: "Visit your favorite nursery and you will find that people classify plants according to their appearance and function, with one group classified as 'trees'. But what genes make trees? This classification method is intuitive and practical, but it is too artificial and unnatural."
Groover adopts the woody characteristics of the tree, which must be a typical characteristic of the tree. "Real" trees make wood through secondary growth, a process that makes the tree grow stronger while growing taller. Secondary growth occurs from a ring of special cells around the stem, called the vascular cambium, that divide in two directions: towards the outer edge of the tree to produce bark and towards the center of the tree to produce xylem.
Year after year, these xylem gradually deposits into new growth circles inside, which are doped with cellulose and a long hard polymer called lignin. After the hardening process of cells, most woody cells are killed and removed, ultimately leaving only a hard cell wall.
Among plants present on earth today, secondary growth may have a single evolutionary origin, although today's tiny Lycopodium and Equisetum invented their own versions about 300 million years ago. For example, the extinct Lycopodium genus can grow to 30 meters high. However, secondary growth does not automatically produce tree characteristics: despite a single origin, woody characteristics appear sporadically throughout the plant family tree; in plants where woody characteristics have disappeared, they reappear.
After plants captured the island, woody characteristics seemed to evolve quite rapidly. For example, there are woody violets on the island of Hawaii and dandelion trees on the Canary Islands.
The concept of wood is actually very flexible, which disguises their literal absoluteness. When you think about the hard stems of sage and lavender, we can see that it is not a matter of the presence or absence of woody structure, but a matter of degree. In 2010, Groover and colleagues wrote in a review published in the New Botanist: "Non-woody herbs and large woody trees can be thought of as two ends of a continuum, and the degree of ligyness of specific plants can be affected by environmental conditions... In fact, the terms 'herb' and 'woody', while practical, cannot distinguish between the differences in woody degrees of the large number of plants classified into these categories and the huge differences in their anatomical structure."
Molecular biology can provide some insight into why the ability to make wood has been preserved and frequently reappears during plant evolution. Whether for trees or plants that are not trees, genes involved in regulating shoot growth during their primary growth are also active during secondary growth that produces woody structures. This suggests that these genes, which already existed during primary growth and are indispensable for bud growth, have shifted to new roles during woody evolution. This may explain evolutionarily why the ability to make wood is preserved in non-woody plants, and why it is relatively easy to restore.
In other words, a plant does not need to have a wooden structure to become a tree. Among monocotyledons that have lost their ability to secondary growth, some members are not "real" trees, but do look like trees. For example, banana plants can grow to 3 meters high. What they look like trunks is actually a "false stem" made up of tightly wrapped, overlapping leaf sheaths. The real stem only appears when it is in bloom, and it will stick out of the leaf sheaths itself. Palms are also monocotyledons. They can grow taller by stretching thick branches with huge buds on top, but their stems do not get thicker as they grow taller.
4. Not only do genes such as longevity and woody structure fail to clearly tell us what a tree is, but it is also difficult for analysis of tree genomes to tell us what the decisive characteristics of trees are. Since 2006, geneticist David Neale and colleagues have carefully studied the sequencing results of 41 plant genomes. They found that trees that produce edible fruits have a large number of genes for making and transporting sugar compared to trees that produce non-edible fruits; but this is true for grapes, which are woody vines, and tomatoes, which are herbaceous plants.
In addition, several trees, such as spruce, apples and some eucalyptus, have extended genes that resist environmental stresses such as drought and severe cold; but the same is true for many herb plants, such as spinach and Arabidopsis, but they are nothing like trees.
So far, we have not found prominent genes or genomes that can confer characteristics on plant trees. Are trees related to complexity? No. Genome-wide duplication, often used as a token of complexity, is prevalent throughout the plant kingdom. Is that related to the size of the genome? Not really. The largest plant genomes come from the clover, and the smallest plant genomes come from Utricularia spirulina. They are both herbaceous plants. The former is a colorful white floret herb, and the latter is a tiny carnivorous plant that feeds on protozoans.
Neale believes that tree characteristics may be more related to which genes are turned on than which genes are present. "From a genomic perspective, trees and herbs basically have exactly the same material. Trees are big, they are wooden and can transport water from the ground to high places. But there seems to be no profound and unique biological principle that distinguishes trees from herbs."
Although it is difficult to define what a tree is, it has some undeniable advantages-it allows plants to use high spaces, where they can absorb sunlight, spread pollen and seeds, and suffer less interference than plants that remain on the ground. So maybe it's time to start thinking of "tree" as a verb rather than a noun, which means "as a tree", or "treeization." It's a strategy, a way of survival, like swimming or flying, although in our view "being a tree" happens in a very slow motion. The tree lives on and on until the arrival of an axe, a pest, or a bolt of lightning that can chop it down.
The above is the information and characteristics of the tree and the detailed introduction of the tree. Do green plant fans understand it?