To date, there are more than 400,000 species of flora on Earth. They all came from just a few ancient plants.
Some species disappeared from the face of the Earth, as they could not adapt to changing conditions or could not withstand competition from other, newly emerged plant species.
The oldest known plants areThe simplest blue-green algae. They were single-celled organisms that functioned with a single cell-deprived cell. Among the blue-green algae there were both unicellular and multicellular organisms capable of carrying out photosynthesis. The process of photosynthesis contributed to the introduction of oxygen into the Earth's atmosphere.
About 2600 million years ago, in the ProterozoicEra, the earth was filled with red and green algae. In the late Paleozoic (Silurian period), the oldest higher plants, called rhyniophytes or psilophytes, arise. They had shoots, but there were no leaves and roots. The rhinophytes reproduced by spores. They grew on land or partially in water.
The appearance of higher spore plants
About 400-360 million years ago there areThe first fern-like and moss-like plants belonging to the higher spore plants. On land, the process of dividing plants into a root, stem and leaf begins, supporting tissues and a vascular system arise.
The first terrestrial plants were small in size. Gradually appeared larger forms of plants - fern-shaped, having roots with root hairs. In the Paleozoic era, the ferns were huge plants that filled the land. But due to the fact that water was needed for their reproduction, they grew only in areas with high humidity.
Gymnosperms and angiosperms
360-280 million years ago (CarboniferousPeriod), seed ferns appeared, which became the ancestors of all gymnosperms. The huge tree-shaped ferns that prevailed at that time gradually die off and form deposits of coal.
In the Permian period of the Paleozoic, the most ancient gymnosperms appear. The dying tree-like ferns are replaced by seed and grassy ferns.
About 240 million years ago,Mesozoic era. In its Triassic period, modern gymnosperms appeared, and in the Jurassic the first angiosperms appeared. They have a flower, inside of which is pollination, fertilization and the formation of the fetus. Angiosperms include trees, shrubs and shrubs.
About 70 million years ago the Cenozoic era begins, the planet is filled with angiosperms and gymnosperms that exist to this day.
The evolution of plants is very complex and long-lastingProcess, as a result of which all the modern variety of plants appeared on the Earth, including algae, ferns, bryophytes and flowering plants.