When it comes to biological diversity, few families can match orchids. Their 28,000 known species (with likely many more still to find) outnumber mammals four to one. This staggering variety makes more sense now that a flower trapped in amber proves they date back at least 45 million years, rather than the 20-30 million of the previous record-holder.
As with other flowers, orchids don't fossilize well, so we have just eight ancient specimens with which to trace their evolution. However, in between discovering weird and wonderful extinct insects trapped in amber, Professor emeritus George Poinar, Jr., of Oregon State University has opened up a new window into our understanding of prehistoric flowers. “We’re beginning to locate pollen evidence associated with insects trapped in amber, opening the door to some new discoveries,” Poinar said in a statement.
Orchids keep their pollen in aggregations known as pollinaria, which hitch a ride on pollinating insects to other flowers. Some 45-55 million years ago, when northern Europe was subtropical, a female fungus gnat got a pollinaria stuck to the base of her hind leg, before becoming far more seriously stuck in amber.
The amber was dug up on the Samland Peninsula near the Baltic Sea, and announced in the Botanical Journal of the Linnean Society, with the orchid named Succinanthera baltica. The gnat is so perfectly preserved we can see a drop of blood from its broken leg.
Although the discovery indicates orchids date back at least to the Eocene, molecular dating suggests they may predate the extinction of the dinosaurs.
Geneticist J.S. Haldane was once quoted as saying “God is inordinately fond of beetles”, having made so many of them. If so, orchids must be favorites as well, since, even without counting hybrids, there are twice as many orchidaceae as species of birds, making them possibly the largest family of flowering plants. Part of the reason is that orchids, in their endless quest to attract pollinators (usually without offering them a nectar reward), have evolved lures highly specific to insect species. These include matching the shape or smell of a certain receptive female insect or producing pheromones male bees use to attract females.
The gnat in this case might have been attracted by a mushroom-like smell. Today, gnats fooled in this way will often lay their eggs in the flower, causing their offspring to die of starvation.
“Though the deception works in different ways, the bottom line is that the orchid is able to draw in pollinating insects, which unwittingly gather pollen that becomes attached to their legs and other body parts,” Poinar said.
Although we think of orchids as ornamental, the family includes vanilla, the flavor ironically often associated with a lack of diversity.
Orchids have developed extraordinary diversity in their colors and shapes to appeal to different species of insects. Im stocker/Shutterstock