Every high school student heard about angiosperms. It is not surprising, because one of the most important branches 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 a modern person sees every day can be attributed to this particular department. And this includes flowers, deciduous trees, shrubs, grass and much more. Yes, despite the fact that they differ in terms of life, size and degree of usefulness, they are all representatives of angiosperms, as they are united by a number of important signs, which we will discuss below.
But to begin with, we 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 experts were able to establish, the first representatives of angiosperms bloomed in the Cretaceous period - about 140 million years ago. So they are contemporaries of dinosaurs that they survived successfully. Of course, during this time, plants have significantly changed - many species died during evolution, and others - in the course of human life. But this did not prevent them from remaining the most common representatives of plants. Whereby?
First of all, the speed of seed development played its role. For example, gymnosperms take several years to do this, while angiosperms form flowers that are pollinated and subsequently produce seeds in a matter of months.
In addition, they managed to put wind, insects and even small birds at their service - all of them are engaged in pollination, allowing plants to actively interbreed, 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 specific niche that they still occupy.
What are the characteristics of these plants
Any person interested in botany will find it useful to know the main features of angiosperms in order to easily recognize them 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 trait that unites hundreds of thousands of plants in one department.
- Pollination is one of the most important stages of plant life. It can be performed in various ways - both by wind, birds, water or insects, or independently, without involving 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 growths, methods of fertilization, triploidy of endosperm cells, and a number of others. But to understand these subtleties, you need to have serious knowledge of botany.
What classes are divided into
Any large department of plants is divided into appropriate classes. Of course, angiosperms are no exception. Experts distinguish here classes of dicotyledonous and monocotyledonous. How do they differ and how to identify them? We will tell about this.
By the external characteristics of the plant, it is rather difficult to determine which class it belongs to - you need to know a number of properties and features, as well as keep in mind the numerous exceptions that make classification difficult. It is much easier to look precisely at the seed from which the plant grew.
For example, angiosperms of the monocotyledon class have whole seeds that are not divided in half. This is where most herbs belong - they do not live long, but quickly multiply, reaching the maximum size in a matter of weeks. The root system is fibrous, but not too durable, located not deep 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.
A completely different thing is the dicotyledon class. Their seed, as is understandable, is divided into two parts and has a small germinal root. The root system is pivotal - more durable, able to penetrate several meters deep. This can include not only many types of herbs, but also most trees, shrubs. Pay attention to the flower - it should have a number of petals divisible by four or five without a remainder.
How do they multiply?
Another important point is the propagation of angiosperms.
As mentioned above, they use pollen, which can be transferred from flower to flower in various ways: 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.
By the method of pollination, they can be divided into monoecious and dioecious. The former can multiply, even if they grow separately from other plants of their species. The fact is that their flowers have both staminate and pistillate flowers. The second, for successful extension of the genus, needs other representatives of its species. This is due to the fact that males have only staminate flowers, and females have exclusively pistil flowers.
Pollen forms on the stamens, which should fall on the pistils. In the vast majority of cases, this occurs in a biotic way: self-pollination, pollen transfer by birds or insects. This includes about 80% of angiosperms. About 19% are pollinated by the wind - mainly cereals.
Ripened seeds are often enclosed in a soft and tasty shell - fruits that attract not only people, but also birds and wild animals. Eating fruits with seeds, they all become carriers and contribute to the rapid spread of plants.
Now you know about the propagation of angiosperms.
What is right - angiosperms or flowering?
Quite often, people wonder how to say it right: flowering plants or angiosperms? And also what is the difference between the two?
In fact, there is no difference here. Both the first and second names designate the same department of plants. In addition, sometimes you can hear the third name - secretive. But today it is considered obsolete and practically not used.
Conclusion
As you can see, representatives of the angiosperms are really numerous. And humanity really owes them a lot: from food and clean air to wood and good mood at the sight of magnificent flowers.