Imagine discovering a mammal without mammary glands or an insect with eight legs. Aquatic herbs in the genus Hydatella pose a similar paradox—they lack a defining developmental feature of flowering plants, raising questions about their evolution and rampant speciation during the past 135 million years.
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Evolutionary biologists group together organisms that share unique traits, such as mammary glands or fur, which presumably emerged in a common ancestor. In the flowering plants—the angiosperms—these features include bearing true flowers and key events that occur during fertilization and development.