Negative allometry of leaf xylem conduit diameter and double-wall thickness: implications for implosion safety

# Negative allometry of leaf xylem conduit diameter and double-wall thickness: implications for implosion safety [https://doi.org/10.5061/dryad.b8gtht7mc](https://doi.org/10.5061/dryad.b8gtht7mc) This dataset is part of the manuscript Matos et al., 2024 New Phytol. In this study, we measured leaf xylem conduit double-wall thickness (T) and lumen maximum diameter (D) in > 7,000 conduits of 122 plant species to investigate (1) how *T* versus *D* scaling varies across clades, habitats, growth forms, leaf and vein sizes; and (2) how the *T* versus *D* influences xylem safety against implosion. ## Description of the data and file structure This dataset comprises the following files: **(1) species_list.csv =** a comma separated file containing taxonomic information for the 122 plant species investigated in this study: spp_code = species code comprising the three first letters of the genus and the three first letters of the species name; Species_UCBG = species binomial nomenclature as presented in the University of California Botanical Garden at Berkeley archives; Species_WP = species binomial nomenclature standardized following the world plant database ([https://wfoplantlist.org/);](https://wfoplantlist.org/\);) Genus_WP = genus following the world plant database; Family_WP = family following the world plant database; order_apg4 = order following the APGIV classification (see [https://www.mobot.org/](https://www.mobot.org/)); clade = taxon clade following the APGIV classification: ferns, basal angiosperms, monocots, basal eudicots, rosids, asterids; **(2) species_occurrences.csv** = spatial coordinates (latidute, longitude in decimals) for species occurrences as retrieved from BIEN ([https://bien.nceas.ucsb.edu/bien/](https://bien.nceas.ucsb.edu/bien/) and GBIF ([https://www.gbif.org/](https://www.gbif.org/)) databases. species = species binomial nomenclature following the world plant database; latitude = latitude of species occurrence in decimals; longitude = longitude of species occurrence in decimals; source = source of information about species occurrence. **(3) species_tree.tre** = phylogenetic tree for the 122 plant species investigated in this study saved in .tre format. **(4) implosion_data.csv** = comma separated file containing the data analyzed in this study: Species_name = species binomial nomenclature following the world plant database; order_apg4 = order following the APGIV classification (see [https://www.mobot.org/](https://www.mobot.org/)); clade = taxon clade following the APGIV classification: ferns, basal angiosperms, monocots, basal eudicots, rosids, asterids; growth_form = species growth form: tree, shrub, herb, aquatic, climbing; habitat = species habitat: hydric (Mean Annual Precipitation - MAP > 2000 mm), mesic (500 mm < MAP ≤ 2000 mm) or arid (MAP ≤ 500 mm); leaf size = species leaf size: microphyllous (leaf area - LA ≤ 20.25 cm2), mesophyllous (20.25 < LA < 45 cm2), and macrophyllous (LA ≥ 45 cm2); max_Diameter = leaf xylem conduit lumen maximum diameter in microns; min_Diameter = leaf xylem conduit lumen minimum diameter in μm; Thickness = leaf xylem conduit double cell-wall thickness in μm; TD = ratio between xylem conduit double cell-wall thickness and lumen maximum diameter, dimensionless; O = leaf xylem conduit ovality, calculate as *O* = (*Dmax* - *Dmin*)/(*Dmax* + *Dmin*), where *Dmin* is the minimum conduit lumen diameter in μm and *Dmax* is the maximum conduit lumen diameter. An ovality value of 0 indicates a perfectly rounded conduit Pcri1_low = critical pressure for xylem conduit implosion, calculated following [Blackman et al., 2010](https://doi.org/10.1111/j.1469-8137.2010.03439.x), and using a radial elastic modulus of xylem conduits of 100 MPa. Pcri1_up = critical pressure for xylem conduit implosion, calculated following [Blackman et al., 2010](https://doi.org/10.1111/j.1469-8137.2010.03439.x), and using a radial elastic modulus of xylem conduits of 300 MPa. Pcri2_low = critical pressure for xylem conduit implosion, calculated following [Sperry and Hacke, 2004](https://doi.org/10.3732/ajb.91.3.369), and using a xylem conduit cell wall strength at saturation of 10 MPa. Pcri2_up = critical pressure for xylem conduit implosion, calculated following [Sperry and Hacke, 2004](https://doi.org/10.3732/ajb.91.3.369), and using a xylem conduit cell wall strength at saturation of 80 MPa. vein_order = vein order at which the measured conduit was located: major, medium, minor; LA = one-side leaf area in cm2; Kmax = maximum leaf hydraulic conductance in mmol m-2 s-1 MPa-1; LMA = leaf mass per area in g m-2; TotA = leaf total area included in the analysis of total volume of veins per leaf area, in mm2; TotV = total volume of veins in mm3; VTotV = total volume of veins per unit of leaf area in mm3 mm-2; e = leaf flexural modulus of elasticity in MN m-2; MAP = averaged mean annual precipitation for the species occurrence sites in mm. **(5) anatomy_photos** = a ZIP file that when decompressed contains 122 subfolders named after the Spp_code of each plant species. Inside each species subfolder there are 6-8 leaf cross-sectional microscopic photos saved in Tag Image File Format (TIFF). **(6)** **anatomy_photos_metadata.csv** = comma separated file containing information about the leaf cross-sectional images analyzed in this study: photo_file_name = file names of the leaf cross-sections microscopical photos. spp_code = species code, comprising the first three letters of the genus and the first three letters of the species name. objective = objective (20x, 40x, 100x) at which photo was taken; levels: 20, 40, 100. scale_value = value of scale printed in the photo; levels:1, 10, 100. scale_unit = unit of the scale printed in the photo; levels: micrometer, millimeter. OBS = observations about the photo. ## Code/Software * R-code to reproduce all analysis and figures of the Matos et al., 2024 New Phytologist paper is available at **[https://github.com/ilamatos/xylem_implosion_safety](https://github.com/ilamatos/xylem_implosion_safety).** ## Funding This study was supported by the US National Science Foundation (grant DEB-2025282).