A midrib is the strengthened vein down the middle of a flower petal or leaf. A flower, also known as a bloom or Blossom, is the reproductive structure found in Flowering plants (plants of the division Magnoliophyta, also A petal (from Ancient Greek petalon "leaf" "thin plate" regarded as a highly modified leaf is one member or part of the corolla In Botany, a leaf is an above-ground Plant organ specialized for Photosynthesis.