Stomatal density and size of 12 conifer tree species

This dataset contains stomatal traits from 12 gymnosperm tree species sampled in the research arboretum ARBOfun (Germany, 51°16´ N, 12°30´ E). The data were collected to characterize species differences in stomata density and guard cell length as key traits of a tree species' water-use strategy. Sampling was conducted on sun-exposed, mature canopy shoots from 3 trees per species on 24 June - 1 July 2025. Leaf epidermal imprints were prepared using transparent nail varnish. Microscopic images were taken using a Leica ICC50 W microscope camera at 100x and 1000x magnification. Stomata density was determined from manual counts on 100x images, standardized by field of view area. Stomatal size traits (guard cell length, guard cell pair width, stomatal complex length, stomatal complex width) were measured from calibrated 1000x images using ImageJ. All measurement were quality-controlled and performed by a single observer to ensure consistency. Stomatal trait data are provided in CSV format. Corresponding microscope images are provided as individual TIFF files in a compressed archive.