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Sharp, serrated leaves help trees withstand the cold in winter.
Dr. Dana Royer from the University of Pennsylvania, USA, states that the sharp serrated edges on the leaves store xylem, the tissue responsible for transporting water and nutrients in the sap of the tree. Most of the moisture evaporates through tiny pores along the serrated edges.
“In spring, when trees begin to sprout leaves, serrated leaves lose more water than smooth leaves. This water loss allows the trees to draw up more sap from the roots. Therefore, trees with serrated leaves have a higher rate of sap circulation at the beginning of spring compared to those with round leaves“, said researcher Royer.
“This is extremely important because it provides nutrients for the newly developing leaves, enhancing photosynthesis. In colder climates with shorter growing seasons, serrated leaves can be very beneficial“.
Researchers measured transpiration and photosynthesis activity on the leaves of 60 species of woody plants in two distinct climatic regions: Pennsylvania and North Carolina.
They found that both photosynthesis and transpiration increased by 45% in sharp-leaved trees during the first 30 days of spring. Leaves without serrations did not exhibit such increases. Scientists also discovered that native trees in colder climates, such as York County in southern Pennsylvania, typically have serrated leaves and show vigorous growth.
However, having serrated leaves is not always advantageous for trees, as it can result in greater water loss. Trees in arid regions appear to thrive better with fewer serrations or without serrated leaves at all.
M.T.
