SIAS: Stem Internal Architecture Spectrum: grass stem-architecture trait data and analysis code

Trait data, analysis code and result tables for the hollow-versus-solid stem-architecture dimension of the grasses (Poaceae; Cyperaceae as a solid-stemmed outgroup). DATA: 12,208 Poales species (11,602 Poaceae + 606 Cyperaceae) with stem hollowness and woodiness states compiled from Kew GrassBase, Flora of China (iPlant) and the official Flora of North America Poaceae treatment (2,054 species with documented stem state, 1,448 of them grasses); species- and genus-level environment (GBIF coordinates, WorldClim 2.1, SoilGrids, with CHELSA V2.1 and TerraClimate cross-checks, Last-Glacial-Maximum anomalies and the Global Aridity Index v3); an 11,287-tip Open Tree phylogeny with fossil-calibrated time-tree derivatives; and the result tables behind every manuscript number. CODE: the final analysis and figure chain (phylogenetic logistic regression, dual-axis independence tests, ancestral states, HiSSE/BiSSE diversification, Euler biomechanics, hydraulic bounds, environment PCA, coverage/resolution sensitivity matrices), the regex-extraction protocols for all grass sources, the LLM-extraction protocol of the eudicot screen, and the PCD expression-screen subproject. Entry points: run_all_analyses.sh / reproduce_analyses.sh (R 4.5: phytools, phylolm, MCMCglmm, caper, ape; Python 3.13, see requirements.txt; HiSSE fits included as RDS). NOT REDISTRIBUTED: raw floristic texts, rasters, GBIF downloads, source trees and RNA-seq reads (licensing and size). License: CC BY-NC 4.0 (data and code).