Flowerless gymnosperms, such as conifer and ginkgo, ruled the Jurassic world before their flowering rivals, the angiosperms, became dominant. What caused the fall of one and the rise of the other?
ARGUABLY the world’s weirdest plant, Welwitschia mirabilis is a tangled mass of shredded, fraying leaves in the Namib desert. For a thousand years, perhaps more, it grows just two long leaves, which creep continuously outwards for many metres, becoming torn and ragged. The plant is a lone survivor; fossils suggest its family dates back at least 112 million years to the middle of the Cretaceous, but all its close relatives are gone.
This evolutionary orphan is a gymnosperm – plants that produce seeds, but not true flowers or fruit. The most familiar today are conifers, a group that includes the longest living organisms on Earth, the bristlecone pines, and the coastal redwood, the world’s tallest trees. But gymnosperms also comprise gnetales (like W. mirabilis), the palm-like cycads and ginkgo, also known as the maidenhair tree. When dinosaurs roamed Earth, they walked among the gymnosperms, which dominated the land. But just as the dinosaur era ended with the Cretaceous, so too did the heyday of the gymnosperms. Today, there are only around 1000 species, mostly conifers. They cling on in a world conquered by a quarter of a million angiosperm species – the flowering plants.
What went wrong? Until recently, the tale has been that gymnosperms didn’t stand a chance against these beautiful newcomers. Flowers enabled angiosperms to use insects for pollination, boosting their reproductive success and spurring them on to global dominance. But the latest research reveals new twists in this ancient whodunnit. By better understanding why gymnosperms lost out, we may get some clues about their future, too.
Flowers have long been implicated in the gymnosperms’ demise due to timing: when …