A new discovery shows major flowering plants are 150 million years older than previously thought

Header image: Prof Shuo Wang/Shi et al., 2022, Author provided

Byron Lamont, Curtin University

A major group of flowering plants that are still around today, emerged 150 million years earlier than previously thought, according to a new study published today in Trends in Plant Science. This means flowering plants were around some 50 million years before the dinosaurs.

The plants in question are known as the buckthorn family or Rhamnaceae, a group of trees, shrubs and vines found worldwide. The finding comes from subjecting data on 100-million-year old flowers to powerful molecular clock techniques – as a result, we now know Rhamnaceae arose more than 250 million years ago.

Today, the buckthorn family of shrubs is widespread throughout Africa, Australia, North and South America, Asia and Europe. The important fruit jujube or Chinese date belongs to the Rhamnaceae; other species are used in ornamental horticulture, as sources of medicine, timber and dyes, and to add nitrogen to the soil.

Flowering shoots of the shrub Phylica, now confined to South Africa, have recently been found in amber from Myanmar that is more than 100 million years old.

Together with Tianhua He, a molecular geneticist at Murdoch University, we combined skills to show these new fossils of Phylica could be used to trace the Rhamnaceae family (to which Phylica belongs) back to its origin almost 260 million years ago.

We did this by comparing the DNA of living plants of Phylica against the rate of DNA change over the past 120 million years, to set the molecular clock for the rest of the family.

It was previously believed that Phylica evolved about 20 million years ago and Rhamnaceae about 100 million years ago, so these new dates are much older than botanists