Flowers are one of nature’s most beautiful creations. They give colour to the world, and scent too. But, in evolutionary terms, flowers haven’t been around for very long at all. This week scientists traced back all of today’s flowers to one common ancestor which lived 140 million years ago – before then there were no flowers on Earth.
Flowers may be quite new to the scene but plants themselves are much older. You probably know how mammals and birds evolved from reptiles, which in turn came from amphibians, who were an offspring of fish, who developed from invertebrates… the chain continues back until we get to single-celled organisms like bacteria. But do you know the evolutionary history of plants? Let’s find out…
The earliest lifeforms all got their energy from hydro-thermic vents on the ocean floor. But then, about 3 billion years ago, one type of bacteria made its way to the surface and started using sunlight – photosynthesis had begun. This had massive consequences for life on Earth. Before then there had been very little oxygen but, as photosynthesis caught on, the gas multiplied and this allowed animals to evolve.
For the next 2.5 billion years or so little changed in the world of plants. But then a new, multi-cellular lifeform appeared – algae. There are many different types of algae, from pond scum to seaweed. Technically they are not plants but plants did evolve from them, 500 million years ago.
The next big development came when spores appeared. These could be spread in huge numbers over long distances which boosted plant evolution no end. From only a handful of moss-like plants 500 million years ago, forests of woody plants covered the continents just 150 million years later.
By the time amphibians appeared on land 300 million years ago, plants were the dominant lifeform. Trees some 30 metres tall towered over the landscape and their fossils are what we now burn as coal. By the time the dinosaurs had arrived plants had evolved into a myriad of species – but there were still no flowers.
The first flowers came along 140 million years ago, and they were pollinated by beetles. But then a partnership began which would go on for a very long time. Bees appeared and started to take nectar from flowers. This helped to spread plants’ genes leading to an explosion of flowering species. Today flowering plants are the largest plant family – there are well over a quarter of a million different species, all descendants of that one single species which popped its head up amongst the trampling feet of dinosaurs.
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