Researchers believe they have discovered fossil evidence of the world's oldest flower, at 142 million years: spindly twig with peapod-shped fruit and a woody stem that looks nothing like a rose, an apple blossom or a daisy. The fossil is from an early evolutionary stage when plants were just developing the flowering system that later evolved into fruit, grain, brilliantly coloured and fragrant flowers and food for many animals, said David Dilcher, a University of Florida biology professor.