Magnolia champaca
Figure 1: Flowers of Magnolia champaca (Magnoliaceae) showing the spiral arrangement of floral organs typical of many basal angiosperm lineages.: Wang et al.7 provide new insights into the transition from the spiral to whorled arrangement of floral organs. Photograph courtesy of Walter Judd.

Soltis, D. E. 2016. Floral flexibility: Diversification of the flower. Nature Plants 2:15211. [View at publisher’s site] [View on ResearchGate]


Angiosperm evolution involves a major transition from spiral to whorled arrangements of floral organs. Examination of the genetic programs specifying floral organ identity in Nigella damascene, a species of Ranunculaceae with spiral flowers, illuminates the molecular basis of how spiral flowers can have flexible numbers of floral organs.