For many years, the oldest known flowering plant was Archaefructus (“ancient fruit”) from the famously fossil-rich Yixian Formation of China. This herbaceous aquatic plant has been dated to around 125 million years ago, and even though it apparently lacked the petals and sepals of modern flowers, it had their characteristic reproductive organs - the carpels and stamens.
But a recent reevaluation of a plant fossil discovered more than 100 years ago in Spain may take the “oldest flower” crown off of Archaefructus. Montsechia vidalii was a weed-like plant that lived completely submerged in the shallow waters of Europe’s lakes. Its fossils have been dated to 130-125 million years ago, meaning it was possibly older than Archaefructus.
Researchers from the US, France and Germany have analyzed more than 1,000 fossils of the little plant by painstakingly applying drops of hydrochloric acid to remove the leaves and stems from the rock, carefully bleaching the plant’s protective cuticle to better reveal their shapes and examining the specimen under a stereomicroscope, light microscope and scanning electron microscope.
This precise observation led to a new identification for Montsechia, that being so small and not having the obvious features of angiosperms was not previously recognized as a flowering plant. Even though it also didn’t have petals or nectar-producing structures, Montsechia did have fruits, each containing a single tiny seed.
The humble Montsechia looked much like modern coontails or hornworts, aquatic plants that are commonly used as decoration in ponds and aquariums. Now, paleobotanists are looking for clues to link Montsechia and Archaefructus in the evolutionary journey of angiosperms, and searching for more fossils to help us understand how these few, tiny aquatic seed-bearing plants gave rise to all of the beautiful flowers we see today.
Original findings published in PNAS.