Elucidating the association of trichome and stomatal densities across species

Previous studies suggested a trade-off between trichome density (Dt) and stomatal density (Ds) due to shared cell precursors. We clarified how, when, and why this developmental trade-off may be overcome across species. We derived equations to determine the developmental basis for Dt and Ds in trichome and stomatal indices (it and is), and the sizes of epidermal pavement cells (e), trichome bases (t) and stomata (s), and quantified the importance of these determinants of Dt and Ds for 78 California species. We compiled 17 previous studies of Dt-Ds relationships to determine the commonness of Dt-Ds associations. We modelled the consequences of different Dt-Ds associations for plant carbon balance. Our analyses showed that higher Dt was determined by higher it and lower e, and higher Ds by higher is and lower e. Across California species, positive Dt-Ds coordination arose due to it-is coordination and impacts of the variation in e. A Dt-Ds trade-off was found in only 30% of studies. Heuris..., , , # Elucidating the association of trichome and stomatal densities across species

[https://doi.org/10.5061/dryad.rv15dv4g5](https://doi.org/10.5061/dryad.rv15dv4g5)

The data presented here are leaf trichome and stomatal traits measured for 78 California species from seven diverse California ecosystems, including alpine, chaparral, coastal sage scrub, desert, mixed conifer-broadleaf forest, mixed riparian woodland, and montane wet forest. Fully expanded, mature leaves were collected from each of the five individuals per species. Species average values were calculated from one leaf from each of three individuals per species. The traits presented are anatomical traits of the leaf epidermis, including cell sizes, densities, and indices. Additional details on field sampling and methodology can be found in a previous publication (Medeiros et al., 2023 *Functional Ecology*).

Sampled leaves were fixed in FAA solution, and from these leaves, we quantified epidermal traits from leaf micrograph...