<p>Rising temperatures and longer dry spells are pushing many Indian forests closer to the heat limits of their trees. This article explains how different types of leaves survive heat using different strategies. We first review the basics: how leaves make sugars through photosynthesis, how stomata balance carbon dioxide uptake with water loss (transpiration), and how water is pulled up tall trees by the cohesion–tension mechanism. We then introduce leaf mass per area (LMA), as a simple ‘investment’ measure of leaf design. Drawing on research from tropical dry forests, we show that higher-LMA (tough, long-lived) leaves tend to have higher critical temperatures (T₅₀) but often lower photosynthetic rates, revealing a heat–speed trade-off. We also discuss how drought exposure can increase thermotolerance, why evergreen species often outperform deciduous species in heat tolerance, and how thermal safety margins (T₅₀–maximum leaf temperature) help predict vulnerability under climate change. Understanding these linked traits can improve conservation, reforestation choices, and climate-resilient ecosystem planning. Short classroom activities such as measuring leaf surface temperature and calculating LMA are included to connect concepts with local trees.</p>