OSB archive
OSB archive

Roots, shoots & sex

Pete Wilton

Botany was never a passion of mine, but the more I find out about plant science the more interested I become in our leafy friends.

Did you know, for instance, that in woody plants with separate sexes female plants are usually considerably smaller than male plants of the same species?

Scientists think this is because females invest more resources in reproduction leaving them less resources to power growth.

In a paper just published in Royal Society B, John Pannell and Mark Harris of Oxford's Department of Plant Sciences take a look at a group of plants where the opposite is true: herbs.

So why, in herbs, do female amazons tower above their male counterparts?

To find out the researchers grew males and females of the herb Annual Mercury [Mercurialis annua] but only allowed some of them to reproduce.

John told us: 'Our results suggest that male herbs are smaller than female herbs because they need to allocate resources to the roots needed to harvest nitrogen for pollen production.'

Even for plants, it seems, sexual potency comes at a high evolutionary cost.