125-130 mn year old mythical 'first flower' identified

An international team of paleobotanists has identified a 125-130 million year old freshwater plant as one of earliest flowering plants on Earth.

This aquatic plant named Montsechia vidalii once grew abundantly in freshwater lakes in what are now mountainous regions in Spain.

Fossils of the plant were first discovered more than 100 years ago in the limestone deposits of the Iberian Range in central Spain and in the Montsec Range of the Pyrenees, near the country's border with France.

The study led by Indiana University (IU) paleobotanist David Dilcher and colleagues in Europe represents a major change in the presumed form of one of the planet's earliest flowers known as angiosperms.

"This discovery raises significant questions about the early evolutionary history of flowering plants, as well as the role of these plants in the evolution of other plant and animal life," explained Dilcher, emeritus professor in the IU's Bloomington college of arts and sciences.

In terms of appearance, Montsechia resembles its most modern descendent, identified in the study as Ceratophyllum.

Also known as coontails or hornworts, Ceratophyllum is a dark green aquatic plant whose coarse, tufty leaves make it a popular decoration in modern aquariums and koi ponds.

Also previously proposed as one of the earliest flowers is Archaefructus sinensis, an aquatic plant found in China.

"A 'first flower' is technically a myth, like the 'first human'. But based on this new analysis, we know now that Montsechia is contemporaneous, if not more ancient, than Archaefructus," Dilcher added.

The conclusions are based upon careful analyses of more than 1,000 fossilised remains of Montsechia.

The stems and leaf structures were coaxed from stone by applying hydrochloric acid on a drop-by-drop basis.

The age of the plant at 125-130 million years is based upon comparisons to other fossils in the same area notably the freshwater algae charophytes.

Montsechia possesses no obvious "flower parts" such as petals or nectar-producing structures for attracting insects and lives out its entire life cycle under water.

"The fruit contains a single seed -- the defining characteristic of an angiosperm -- which is borne upside down," Dilcher added.

"The reinterpretation of these fossils provides a fascinating new perspective on a major mystery in plant biology," noted Donald H Les, professor of ecology and evolutionary biology at University of Connecticut.

The finding were reported in the journal Proceedings of the National Academy of Sciences.