Objective The purpose of this study was to investigate the geographic variation among different provenances of Toona sinensis seed traits.

Method Eight phenotypic traits of seeds from different provenances collected from 35 counties in 11 provinces were analyzed.

Result and conclusion The results showed there were significant differences among the different provenances in the traits of seed full length, seed wing length, seed length, seed width, seed thickness, ratio of seed length/width, ratio of seed width/thickness and 100-seed mass.The variation coefficients of ratio of seed length/width was the biggest, and the ratio of seed width/thickness was the smallest, which was 11.16% and 5.64% respectively.The repeatability of 100-seed mass was the biggest, and the seed width/thickness ratio was the smallest, which was 98.1% and 75.5% respectively.Seed length was significantly positively correlated with longitude; seed length and ratio of seed length/width were significantly negatively correlated with latitude.The trend of geographic variation showed that seed sizes decreased from southwest to northeast. Seed thickness was significantly negatively correlated with altitude, but positively correlated with ratio of seed length/width.Seed thickness and 100-seed mass were significantly negatively correlated with average annual temperature, but positively correlated with average annual precipitation, respectively.Seed length and ratio of seed length/width were significantly positively correlated with average annual sunshine time, but seed thickness was significantly negatively correlated with average annual sunshine time.100-seed mass was negatively correlated with ratio of seed width/thickness, but not significantly correlated with ratio of seed length/width.Seed width was significantly positively correlated with seed thickness, but not significantly correlated with seed full length, seed wing length, and seed length.According to the cluster analyses of the 8 traits of T.sinensis, the 35 provenances can be divided into 5 types.