Arizona scientists propose a new scenario to explain why perfectly good, everybody's-equal, bisexual flowers evolve forms with different genders.
A genetic goof that adds extra sets of chromosomes, or polyploidy, could trigger the split into gender forms, suggests Jill S. Miller, now of the University of Colorado in Boulder. She's studied the wolfberries, or Lycium, but other plants may have similar stories, she and Lawrence Venable of the University of Arizona in Tucson argue in the Sept. 29 Science.
"It's something people hadn't really thought about," says plant-gender specialist Lynda Delph of Indiana University in Bloomington. Parts of the scenario had been suggested, but no one had connected them, she notes.
Plants deploy sex organs at least nine ways: bisexual flowers only, male and female flowers on the same plant, all-female plants mixed with bisexuals, and so on. "If you want to study gender, you should study plants," Miller says.