Redwood trees have been studied extensively but only recently did the scientist discover that they have two types of leaves – peripheral leaves and axial leaves – that look different and perform different tasks. They help redwood trees adapt to both wet and dry conditions – an ability that could be key to their survival in a changing climate. Redwoods are among those super-trees that can survive pest attacks, fire and even perhaps climate change. They are also among the planet’s biggest, tallest and oldest trees.
Unlike each other
While the peripheral leaf takes care of the food preparation via photosynthesis, the axial is devoted to absorbing water. A large redwood can absorb up to 14 gallons of water in just the first hour its leaves are wet!
The two types of leaves look different from each other, inside out. When scientists looked at the leaves under a microscope, they understood that they were completely different from each other. The axial leaves were packed with water storage cells, but their phloem- tubes in the leaves that export photosynthetic sugars to the tree – appeared to be blocked and useless.
Adaptation technique
Analysis showed that the redwoods’ axial leaves account for only about 5% of the trees’ total leaf area, and barely produce enough energy through photosynthesis to maintain themselves. But they contribute up to 30% of the trees’ total water absorption capacity.
Together these two types of leaves balance the dual requirements of photosynthesis and water absorption, allowing redwoods to thrive in both wet and dry habitats.
Redwoods are found in both wet and dry environments with intense seasonal variation. In the wet, rainy areas, the axial is found on the tree’s lower branches, leaving the upper, sunnier levels to the peripheral leaf type. This completely flips for redwoods in drier areas: The axial leaves live among the tree’s higher levels to take more advantage of fog and rain, which occur less often in the drier environment.
Picture Credit : Google
