Some plant leaves grow from small size to normal size by cell enlargement and/or cell proliferation. Other leaves or most flowers not only grow but also unroll or unfold from buds.
The petals and the petal ribs of a morning glory flower mysteriously spiral in a bud. These buds have a spindle shape with spirally striped pattern as shown in today’s photograph.
During unfolding of morning glory flowers, the spiral stripes loosen, and the petals are drawn from the chinks of the stripes. After 3 to 6 hours, funnel shaped flowers magically appear.
The opening of morning glory flowers has been studied with time lapse video. Many fascinating films can be watch on the Internet, e.g., that of Joshua Puzey or Niche Garden.