Leaf veins loopy for a reason
Circular networks are best for getting around a bad spot, varying load
By Laura Sanders
Web edition : Tuesday, February 2nd, 2010
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Avoiding a bad spotVeins’ looped network allows water and nutrients to flow around an injury (green dot) on the main vein of a lemon leaf. E. Katifori et al/PRL 2010
Treebranches have inspired efficient transit networks, but a new studyfinds inspiration in leaves. The curvy, connected leaf veins found insome plants are an efficient way to circumvent damaged areas andchannel nutrients, report researchers led by Eleni Katifori of theRockefeller University in New York City.
“It’s obvious that ifyou look at leaves, they have a lot of loops,” Katifori says. To findout how the looped networks may be beneficial for the plants, theresearchers created a computer model to compare how efficientlydifferent branching patterns could do the job of leaf veins, which movewater and nutrients around. “The question we’re asking is, what’s thebest network we can build?” Katifori says.
In the simulations,the looped network performed better than nonlooped ones in severalimportant ways, the team reported January 29 in Physical Review Letters.Damage from hungry insects, cold weather or parasites can interruptleaves’ normal venation patterns. Connected circular veins allowed theflow of water and minerals to circumvent areas where veins weredestroyed, the team shows. The looped network also allowed leaves toeasily adjust the flow rate of water through veins, which can helpleaves conserve water on a hot day, Katifori says.
Loop networksaren’t found just in tree leaves. Blood vessels in the retina,structural veins in insect wings and the architecture of certain coralsare all based on loops, the researchers write. Understanding thebenefits of such networks might lead to more efficient man-made networkdesigns.