Variation in root hair traits in 75 xerophytic species: Constraints of phylogeny, trait trade-offs and environment

Root hairs play an important role in the acquisition of soil resources by increasing absorptive surface area. Yet, key factors driving the variation of root hair traits across different species along biogeographic gradients are still poorly quantified, limiting our understanding of the functional relevance of root hairs. We measured root hair length, diameter and areal density of 75 xerophytic species across a 1000-km, latitudinal gradient in a dry valley system. The influences of phylogeny, environment, and fine-root morpho-anatomical traits on root hairs were quantified. We found that 95% of sampled species had root hairs, total absorptive root area increased by roughly 0.3% for species with very few roots hairs, and up to a 180% for species with large and dense root hairs. Phylogeny did not appear to be a significant factor influencing root hair traits. Root hair diameter and length were positively related to root diameter and cortex thickness, while root hair densities were negative..., , , # Variation in root hair traits in 75 xerophytic species: Constraints of phylogeny, trait trade-offs and environment

[https://doi.org/10.5061/dryad.jq2bvq8md](https://doi.org/10.5061/dryad.jq2bvq8md)

## Description of the data and file structure

The mean values of root hair traits of 75 species were showed in first subtable

RHL: root hair length (um);
RHD: root hair diameter (um);
RHdn: root hair number density (um);
RHds: root hair surface area density (mm2. mm−2).

Data at species-site level along latitudinal gradient was showed in second subtable , including environmental factors.
MAT: Mean annual temperature (°C);
MAP: mean annual precipitation (mm);
AI: aridity index; DOC: dissolved organic carbon (mg/kg);
TP: total soil phosphorus (g/kg);
TIN: total inorganic nitrogen (mg/kg).

Environmental factor data are incomplete (marked as 'null') because some samples were missing.
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