Flowers are more than objects that awaken passions: they were key evolutionary innovations leading to rapid diversification and the current dominance of flowering plants in terrestrial ecosystems. However, the only biological function that has been ascribed to petals is to mediate interactions with pollinators. Here we show that petal surfaces can effectively capture and quickly deliver nitrogen (N) ions available in atmospheric deposition to ovaries and seeds. In laboratory and field experiments we used 15N tracers in concentrations that mimicked concentrations in natural rainfall.
Results/Conclusions
We found significant 15N enrichment in seeds when petals were exposed to 15N tracers, contrasting with the lack of enrichment when 15N tracers were applied just to soil or foliage. Translocation rates of 15N were also much faster through petals than through foliage. Although it is well known that plant foliage directly intake reactive N from the atmosphere, previous studies have not examined the role that flower structures could play in N intake and allocation to seeds. Our results suggest that flower petals can contribute to plant fitness not only as organs of display, but also as permeable surfaces that can opportunistically help reproductive structures to meet demands of limiting nutrients and reproductive costs.
