The equation can generate many, but not all, leaf arrangement patterns observed in nature by changing the value of different variables of plant physiology, such as the relationships between different plant organs or strength of chemical signals within the plant. Leaf arrangement has been modeled mathematically since 1996 using an equation known as the DC2 (Douady and Couder 2). Sugiyama's research team began their investigation by doing exhaustive testing of the existing mathematical equation used to model leaf arrangement.
"Our research has the potential to truly understand beautiful patterns in nature," said Sugiyama. Japonica leaves are 180 degrees, 90 degrees, 180 degrees, 270 degrees, and then the next leaf resets the pattern to 180 degrees. The peculiar pattern that Sugiyama's research team studied is called "orixate" after the species Orixa japonica, a shrub native to Japan, China, and the Korean peninsula. To identify the leaf arrangement of a plant species, botanists measure the angle between leaves, moving up the stem from oldest to youngest leaf.Ĭommon patterns are symmetrical and have leaves arranged at regular intervals of 90 degrees (basil or mint), 180 degrees (stem grasses, like bamboo), or in Fibonacci golden angle spirals (like the needles on some spherical cacti, or the succulent spiral aloe). But in fact, it more accurately reflects not only the nature of one specific plant, but the range of diversity of almost all leaf arrangement patterns observed in nature," said Associate Professor Munetaka Sugiyama from the University of Tokyo's Koishikawa Botanical Garden. "We developed the new model to explain one peculiar leaf arrangement pattern. A Japanese plant species with a peculiar leaf pattern recently revealed unexpected insight into how almost all plants control their leaf arrangement.
However, the details of how plants control their leaf arrangement have remained a persistent mystery in botany. Leaves can be enjoyed for their shade, autumn colors, or taste, and the arrangement of leaves on a plant is a practical way to identify a species. view moreĬredit: Image by Takaaki Yonekura, CC-BY-ND (Creative Commons, By Attribution, No Derivatives). Researchers at the University of Tokyo recently improved the equation that is used to calculate leaf arrangement patterns by studying the unusual pattern of Orixa japonica. Common alternate types are distichous phyllotaxis (bamboo) and Fibonacci spiral phyllotaxis (the succulent spiral aloe), and common whorled types are decussate phyllotaxis (basil or mint) and tricussate phyllotaxis (Nerium oleander, sometimes known as dogbane). Image: Leaf arrangement with one leaf per node is called alternate phyllotaxis whereas arrangement with two or more leaves per node is called whorled phyllotaxis.
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