The Institute of Low Temperature Science, Hokkaido University, Sapporo 060, Japan
(Received July 5, 1988; Accepted August 18, 1988)
Keywords: Foliage, Leaf-Shape, Leaf-Size, Phenology, Seasonal Dynamics
Abstract. Seasonality in plant growth and development is a universal phenomenon in regions with higher altitudes. Both we and insects can recognize the beauty and seasonal changes in plant structures by yearly changes in size, shape and color. However, it has been difficult to quantify the shape. To describe the competent seasonal dynamics in plant foliage, simple measurements of sizes and shapes were tried on extended radical leaves of adult plants of Geum japonicum for a year. Five size parameters (length and area) and 5 shape indices (distances from a circle and a line, length/width rate) were measured on excised leaves and compared relatively by month. Size parameters were synchronized with each other and showed two peaks, in June and late August, while shape indices varied in their seasonal changes and a major and two minor peaks were found. The seasonal dynamics of relative changes in leaf shape seemed not to be correlated with the changes in leaf size; particularly, autumn leaves looked simpler and pre-wintering leaves looked more complex, even if the same size. Elegant phenological changes in plant foliage structure seemed to be combined with different patterns in shape and size changes in nature.