Field of Science

Friday Fabulous Flower - How orderly!

The study of flowers at early stages of development requires nerves of steel for the delicate dissections. To really see what's going on the specimens are observed with a scanning electron microscope, and at early stages, flowers often reveal similarities and differences critical to understanding their evolutionary diversification, that is, how diversity in floral form arises from a basic plan. Here's a false color image of the androecium of a species of Anaxagorea, the basal genus of custard apple family. The early development of this flower shows a very orderly development of the androecium and gynoecium (perianth parts have been removed), 12 ranks, each rank consisting of 2-3 stamens, a staminode, and 1-2 pistils, and one pistil in the center. The numbers and orderliness tell us that within this lineage floral diversity has shifted to fewer parted and simpler flowers and to many more parted flowers of greater complexity. For comparison, here's the flower at maturity, fully open and functional. The parts you see in the SEM image are enclosed within 3 whorls of 3-parted perianth, and no, this is not a monocot, but a woody dicot in the Magnoliales. Thanks to AoB blog.

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