Every high school student has heard of angiosperms. It is not surprising, because one of the most important sections of botany is devoted to them. In addition, representatives of angiosperms literally surround us, meeting at every step.
What are angiosperms?
The vast majority of plants that modern man sees every day can be attributed to this department. And this includes flowers, deciduous trees, shrubs, grass and much more. Yes, despite the fact that they differ in life span, size and degree of usefulness, they are all representatives of angiosperms, as they are united by a number of important features, which we will discuss below.
But first, let's find out when these plants first appeared on our planet and thanks to which they managed to achieve dominance.
When they appeared on Earth
As the experts managed to establish, the first representatives of angiosperms bloomed in the Cretaceous period - about 140 million years ago. So they are contemporaries of the dinosaurs, which they successfully outlived. Of course, during this time, plants have changed significantly - many species have died in the course of evolution, and others - in the course of human life. But this did not prevent them from remaining the most common representatives of plants. Thanks to what?
First of all, the speed of seed development played its role. For example, in gymnosperms it takes several years, while angiosperms form flowers that are pollinated and subsequently produce seeds in a matter of months.
In addition, they have harnessed the wind, insects and even small birds, all of which are pollinators, allowing plants to interbreed actively, achieving maximum genetic diversity, which ensures a high level of survival.
Finally, it was the competition between species that placed each of the plants in a certain niche, which they occupy to this day.
What features do these plants have
Anyone with an interest in botany would benefit from knowing the basic features of angiosperms so that they can be easily identified at a glance. There are quite a lot of them, so we list only the most basic, understandable and interesting to most ordinary people, and not just highly specialized scientists:
- The presence of a flower - it can be noticeable, beautiful and catchy, or distinguishable only under a microscope. But it is this feature that unites hundreds of thousands of plants into one department.
- Pollination is one of the most important stages of lifeplants. It can be performed in various ways - both by wind, birds, water or insects, and independently, without the involvement of extraneous organisms.
- Seeds contain nutrients that provide nutrition to the young sprout in the first days or weeks of life - before the root system becomes powerful enough to cope with this task on its own.
Of course, there are other signs of angiosperms - the presence of female and male shoots, methods of fertilization, triploidity of endosperm cells and a number of others. But to understand such subtleties, you need to have serious knowledge of botany.
What classes are divided into
Any major department of plants is divided into corresponding classes. Of course, angiosperms are no exception. Experts distinguish here the classes of dicots and monocots. How do they differ and how to recognize them? Let's talk about this.
It is rather difficult to determine which class it belongs to by the external signs of a plant - you need to know a number of properties and features, as well as remember the numerous exceptions that greatly complicate the classification. It is much easier to look exactly at the seed from which the plant has grown.
For example, monocotyledonous angiosperms have whole seeds that are not split in half. This is where most grasses belong - they do not live long, but they multiply rapidly, reaching their maximum size in a matter of weeks. The root system is fibrous, but not too durable, locatedshallow from the surface of the earth. Flowers in most cases have a number of petals that is a multiple of three or, much less often, four. But it never happens that their number is divisible by five without a remainder.
It's a completely different matter - the class of dicots. Their seed, as you know, is divided into two parts and has a small germinal root. The root system is pivotal - more durable, capable of penetrating several meters deep. This includes not only many types of grasses, but also most trees and shrubs. Pay attention to the flower - it should have a number of petals divisible by four or five without a trace.
How do they reproduce
Another important point is the reproduction of angiosperms.
As mentioned above, they use pollen, which can be transferred from flower to flower in various ways: by wind, water, insects or birds. There are also self-pollinating, in which pollination occurs right inside the flower before it opens. But their number is relatively small.
According to the method of pollination, they can be divided into monoecious and dioecious. The former can reproduce even if they grow separately from other plants of their species. The fact is that their flowers have both staminate and pistillate flowers. The latter, for the successful extension of the genus, need other representatives of their species. This is due to the fact that males have only staminate flowers, while females are exclusively pistillate.
Pollen is formed on the stamens, which should fall onpistils. In the vast majority of cases, this occurs in a biotic way: self-pollination, the transfer of pollen by birds or insects. This includes about 80% of angiosperms. Another 19% is wind-pollinated, mostly cereals.
Ripe seeds are often enclosed in a soft and tasty shell - fruits that attract not only people, but also birds and wild animals. Eating fruits along with seeds, they all become carriers and contribute to the rapid spread of plants.
Now you know how angiosperms reproduce.
Which is correct - angiosperms or flowering?
Quite often people ask themselves the question of how to say: flowering plants or angiosperms? And also what is the difference between them?
There really is no difference here. Both the first and second names denote the same department of plants. In addition, sometimes you can hear the third name - secretive seeds. But today it is considered obsolete and is practically not used.
Conclusion
As you can see, representatives of angiosperms are really numerous. And humanity really owes them a lot: from food and clean air, to wood and a wonderful mood at the sight of luxurious flowers.
