In dry regions, the leaf size of a tree becomes smaller. It is so to

In dry regions, plants known as xerophytes exhibit various morphological adaptations to survive water scarcity. A primary adaptation is the reduction of leaf size to minimize the surface area exposed to the atmosphere [1]. Transpiration is the process where water vapor is lost through the aerial parts of a plant, primarily the leaves [2]. By having smaller, thicker, or needle-shaped leaves, plants significantly reduce the number of stomata and the total area available for evaporation, thereby checking excessive transpiration [1]. This reduction in surface-area-to-volume ratio helps maintain the plant's internal water balance during prolonged droughts and intense heat [3]. While other features like waxy cuticles or bad-tasting tissues also exist to retard water loss or discourage herbivores, the specific reduction in leaf size is fundamentally a mechanism to conserve water by limiting transpiration [4].

Sources

1. [1] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 23: The Cool Temperate Continental (Siberian) Climate > Relationship between Glimate and Natural Vegetation > p. 220
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > Activity 5.8 > p. 95
3. [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 30: Climatic Regions > Natural Vegetation In The Mediterranean Climate > p. 449
4. [4] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > 10. Desert Biomes > p. 15