Persea Flower Diagram

May 21, 2009

This flower from an avocado tree (Persea americana) shows the characteristics of ancient flowering-plant lineages. Its petals (colorful in most flowers) and sepals (usually a green outer layer) are combined into one organ.
The flower is one of the key innovations of evolution, responsible for a massive burst of evolution that has resulted in perhaps as many as 400,000 angiosperm species. Before flowering plants emerged, the seed-bearing plant world was dominated by gymnosperms, which have cone-like structures instead of flowers and include pine trees, sago palms and ginkgos.
“What we found is that the flower of Persea is a genetic fossil, still carrying genetic instructions that would have allowed for the transformation of cones into flowers,”
“Although the organs are developing to ultimately become different things, from a genetic developmental perspective, they share much more than you would expect,” Chanderbali said. “As you go back in time, the borders fade to a blur.”
Researchers don’t know exactly which gymnosperms gave rise to flowering plants, but previous research suggests some genetic program in the gymnosperms was modified to make the first flower, Soltis said. A pine tree produces pine cones that are either male or female, unlike flowers, which contain both male and female parts. But a male pine cone has almost everything that a flower has in terms of its genetic wiring.