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The distributions of long chain n-alkanes are often utilized as plant-derived paleoenvironmental proxies. However, there is debate regarding the degree to which photosynthetic pathway, temperature and/or hydrology drive the variation in chain length distribution observed among different environments. In order to assess the influence of temperature and photosynthetic pathway on plant n-alkanes, this study examined n-alkane chain length distributions in plants and soils along a transect across mid-continental USA spanning > 20 °C mean annual temperature with a limited range of mean annual precipitation. We found that (i) longer chain length in plants and soils correlated with higher growing season temperature, with relative humidity also a possible driver, (ii) soils exhibited a stronger correlation with temperature than did individual plants, which may reflect the averaging of plant input to soils and (iii) average …