Intraspecific leaf morphometric diversity in the endangered and narrow endemic Quercus trojana subsp. euboica (Fagaceae): a quantitative dataset from three natural populations in Euboea, Greece.

This study provides the first quantitative dataset on leaf morphometric diversity for Quercus trojana subsp. euboica (Papaioannou) K.I.Chr., a narrow endemic oak of Greece. This subspecies is of high conservation priority, listed in the Red Data Book of Rare and Threatened Plants of Greece and its restricted range in Northern Euboea was heavily impacted by a catastrophic wildfire in 2021. We sampled 301 leaves from three natural populations (Kerasia1, Kerasia2 and Prokopi) and processed them using a custom Python pipeline to extract 14 size and shape variables. Statistical analyses (PCA and LDA) showed that, while leaf shape remains relatively stable across populations, there is significant variation in leaf size. Specifically, the Prokopi population, where only understorey individuals were found, had much larger leaves (mean leaf area 1,015 mm2) than those in Kerasia1 (648 mm2) and Kerasia2 (715 mm2). These data establish a baseline for monitoring the species' recovery and will be used alongside future genomic data to better understand the role of phenotypic plasticity in its conservation.