By Susan Milius
Plants with buds the size of basketballs, which open flowers up to a meter across, must be reclassified as relatives of poinsettias, say researchers who’ve examined the DNA of the world’s largest known flowers.
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For almost 2 centuries, botanists have debated where rafflesia plants, with their odd flowers, sit on the plant family tree. Early observers asked whether they were flowering plants or fungi. Later, botanists disagreed about the plants’ nearest relatives. Some pointed to passionflowers, with their elaborate collars and fused sex organs, while others argued for pipevines, with their big, meat-colored flowers.