The first flower to appear along the path of plant evolution, during the time of the dinosaurs, was a hermaphrodite with petal-like organs arranged in concentric circles, researchers said Monday. The bloom had both male and female reproductive organs at the centre, surrounded by multiple layers or "whorls" of petal-like parts called tepals, arranged in sets of three per layer, they wrote in the journal Nature Communications. The reconstruction, based on the largest dataset of flower traits ever assembled -- from 792 existing species -- challenges scientific assumptions that the ancestral flower would have had its sex organs and "petals" arranged in a spiral.