@ WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev

Three was the magic number for the very first flowering plant. The largest study into their early evolution has concluded that its flowers probably had petal-like tepals and pollen-bearing stamens arranged in layered whorls of three. It bore similarities with magnolias, buttercups and laurels – but was unlike any living flower.

The origin of flowering plants and their rapid conquest of the world’s habitats has been a puzzle for nearly a century and a half. In 1879, Charles Darwin described it as an “abominable mystery” that flowers had evolved so late in the history of life yet were still able to take over from the more ancient seed-bearing pines and cycads.

Today, flowering plants account for nine out of every 10 plants – meaning they far outnumber the once-dominant seed plants like conifers that emerged between 350 and 310 million years ago.

Three-dimensional model of the ancestral flower reconstructed

Studying their evolutionary roots is tricky, though: the delicacy of flowers means they rarely become fossilised. The oldest so far discovered is the 130- million-year-old aquatic plant Montsechia vidalii unearthed in Spain in 2015. However it is thought that flowering plants first appeared much earlier than this, sometime between 250 and 140 million years ago.

Picking flower traits

To unravel what the very first flower was like, a 36-strong team led by Hervé Sauquet of the University of Paris-South, France, spent six years analysing the anatomical evidence of nearly every type of flowering plant to identify their most ancestral traits.

They calibrated their results with dates derived from molecular analyses and constructed evolutionary trees that modelled the earliest stages in flower evolution.

“We looked at the big bang of flowering plant evolution when they first evolved,” says Sauquet.

They discovered that the first flower probably had 11 or more tepals and stamens, generally grouped in threes and carried both male and female reproductive structures. It was arranged in a unique way unlike any living flower. It’s unclear how large the first flower was, but it may have been just 1 centimetre or less in diameter.

One surprise is how many petal-like tepals the first flower had compared with most living flowers. Reducing their number allowed later flowers to develop a dazzling array of specialised shapes and sizes and consequently diversify along with their animal pollinators into the enormous range of ecosystems  they occupy today. There are some 300,000 living flowering plants.

The findings mean that the living flowers identified as being most ancient, such as Amborella from New Caledonia, and water lilies, are actually quite evolved compared with their ancient ancestors.

Source: Article By James O’Donoghue,www.newscientist.com

@ WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev