James Dalling, a professor at the University of Illinois at Urbana-Champaign, and his colleagues were studying plants in a forest reserve in Panama when they noticed something interesting about the cypress tree, which is only found in Panama. Typically, once a fern's leaves die back, the plant no longer needs them. But this is not the case for the cypress. Its dead leaves will turn into "zombie leaves" and absorb nutrients from the soil.
When a plant's leaves die, wilt, and droop to the ground, tiny roots grow from the ends of those leaves to connect them to the soil. Subsequent laboratory tests showed that when this happens, the plant reverses the flow of water in these leaves, using them to draw nitrogen from the soil.
So why don’t other plants adopt this practice?
The plant only grows a few centimeters per year, and nutrients are unevenly distributed in the soil in the area, so the plant has to make its growth really work. So instead of investing its energy in growing a specialized, nutrient-seeking root structure that may never reach fertile soil, the plant recycles the leaves it has already grown for photosynthesis.
The plant's arrangement of feeding itself by reconfiguring its own dead tissue has never been documented before. Darling believes that other scientists had not noticed this phenomenon in the phylloxera simply because the leaves looked like decaying plant matter.
"This is a truly novel form of tissue repurposing. It's very different from what we know other ferns do," the researchers said.
The research is described in a paper recently published in the journal Ecology. Watch the video below for more information.