(ORDO NEWS) — The drought caused the plants’ vascular system to change, allowing them to spread across the planet. A study by paleontologists from Yale University.
The first plants to appear on land grew in humid areas near ponds and rivers. Then, about 400 million years ago, they “greened” the entire planet. However, scientists still cannot understand what triggered this process.
To answer this question, the team of researchers studied the structure of the vascular systems in modern plants and in fossils.
As it turned out, when the plants begin to dry out, air bubbles get stuck in the xylem – the water-conducting tissue – and block the movement of water.
The cylinder-shaped vascular systems of the earliest land plants initially served them well in near-aquatic habitats.
But when they moved to land with less water resources, the plants faced the bubble problem described above.
To combat this, early land plants changed the original cylindrical xylem to a more complex one, which helped prevent air bubbles from spreading.
“It didn’t just happen. There is a good evolutionary reason for this change. This happened due to drought. Each time the shape of the vascular system changes, the plant becomes more drought tolerant.
Only the constant presence of drought during that period could cause the plants to complicate the form and populate the entire planet, ”the scientists explained.
These changes occurred quite quickly by the standards of evolution, in about 20-40 million years. According to scientists, their discovery will help develop new plant species that can better tolerate drought caused by climate change.
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