The world's largest flower, called Rafflesia, can have a diameter up to one meter and can weigh up to 10 kilograms. It also smells like rotting fleshRafflesia is a parasitic plant that lacks roots, stems, and leaves. Usually botanists trace plant orders using chloroplast DNA, but since Rafflesia does not have chloroplast genes, Todd Barkman, assistant professor of biological sciences at Western Michigan University, and his team instead analyzed the Rafflesia's mitochondrial DNA (mtDNA), which corresponds to chloroplast DNA.