Study of Flower Petals Shows Evolution at the Cellular Level

The findings are reported by a scientist from UC Santa Barbara and a research team from Harvard University in the Proceedings of the Royal Society B this week.

Columbine flowers, known as Aquilegia, evolved several lengths of petal spurs that match the tongue lengths of their pollinators, including bees, hummingbirds, and hawkmoths. The petal spurs are shaped like a tubular pocket and contain nectar at the tip. The spurs grow from 1 to 16 centimeters in length, depending on the species.

The research team discovered that longer spurs result from the lengthening of cells in one direction, called anisotropy, and not from an increased number of cells. This finding contradicts decades of scientific thinking that assumed the elongated petals form via continued cell divisions.