Even plants like a sugar rush. Or so researchers have discovered while studying the sweetness of sap, which carries sugars from a plant's leaves to other locales, such as the roots. Plants face a tricky balancing act as they load sugar into their sap. Sap with too much sugar is too thick to flow easily, but sap with too little sugar makes for inefficient transport. In today's Journal of the Royal Society Interface, researchers say they devised a mathematical model that predicts the sweet spot for sap: 23.5% sugar by weight. That's far sweeter than Coke, which is 10% sugar. The researchers dug through the literature and found sap sugar-levels for 41 plants, which together average roughly 18%—not far from the model's predictions. The outliers include maize (41%; pictured above) and potato (50%), suggesting that humans have domesticated plants that are on a natural sugar high.
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