A study of a little yellow flower could add a new arrow to textbook drawings of the nitrogen cycle.
The horseshoe vetch (Hippocrepis comosa), a European relative of beans, is the first plant discovered to break down nitrogen-containing compounds in its tissues into a readily usable nitrate form, report Charles Hipkin of the University of Wales in Swansea and his colleagues. Textbook diagrams of the nitrogen cycle now show only microbes performing that task, Hipkin and his colleagues say in the July 1 Nature.
"This is the first paper I have seen that shows plants doing it," says Josh Schimel of the University of California, Santa Barbara.
When Hipkin and his colleagues were surveying the nitrogen chemistry of legumes, they stumb