My PhD focuses on Dipterocarpaceae, the world’s tallest tropical tree family, examining how xylem vessel anatomy scales from small understory trees to emergent canopy giants. I investigate how vessel diameter changes along the vertical axis, focusing on tip-to-base scaling rates and variations within stems and canopies. I also examine the relationship between pit membrane ultrastructure and vessel anatomy as they scale vertically across tree sizes, and how tree height influences the coordination between vessel density, lumen fraction, and vessel size—assessing the implications of these relationships for hydraulic efficiency. Additionally, I explore how microenvironmental conditions influence these scaling patterns.