How Flower Petals Shape Up: Spring Blooms Reveal Science of Plants

Roses, violets, daisies and daffodils are all pretty to look at, but they also all have their own unique petal shapes. As spring finally emerges from winter, researchers are examining exactly what causes flowers to develop these petals. Now, they've discovered a hidden map located within the plant's growing buds that controls a blossom's form.

Leaves and petals perform different functions related to their shape. While leaves are the workers of the plant, acquiring sugars via photosynthesis, petals are the beauty queens of the plant; they attract pollinators with their bright colors. In earlier work, the research team discovered that leaves in the plant Arabidopsis contain a hidden map that orients growth in a pattern that converges toward the tip of the bud. This gives leaves their characteristic pointed tips.

Arabidopsis are small flowering plants that are related to cabbage and mustard. The genus itself actually contains thale cress, one of the model organisms used for studying plant biology, and the first plant to have its genome sequenced. This new study actually focused on the petals of this plant.

So what did researchers find? They discovered that the pattern of growth in petals is different to that in leaves. While it contains a similar hidden map that orients growth in the flower's bud, the pattern of growth is oriented toward the edge. This gives a more rounded shape to the petal and also accounts for the different shapes of leaves and petals. In addition, the scientists found that the molecules called PIN proteins are involved in this oriented growth.

"The discovery of these hidden polarity maps was a real surprise and provides a simple explanation for how different shapes can be generated," said Enrico Coen, senior author of the study, in a news release.

The findings help explain how plants create different shaped organs, despite being unable to move and migrate to form structures of a particular shape. From an evolutionary perspective, the system creates the flexibility needed for plant organs to adapt to their environment and develop different functions.

The findings are published in the journal PLOS Biology.