| The ephemeroid plants are an important and unique component of the early spring herbaceous plants community in Junggar Basin of China. The study on relationship between biomass allocation and allometric growth in ephemeroid plants will contribute to deepen understanding about their survival strategy and ecological function. Sterigmostemum tomentosum, S. fuhaiense, and S. sulfureum were used, the total plant biomass of mature individuals were obtained by using excavation in the field, and organ biomass, allocation ratios and the allometric relationships among the three species were compared. The results showed significant difference in organ biomass and biomass allocation ratios among the three species. S. fuhaiense had the largest biomass, but its ratio of root to shoot (R/S) and the ratio of leaf to shoot (L/S) were the lowest. S. tomentosum had the smallest biomass, but L/S was the largest. S. sulfureum showed the largest R/S. The R/S of S. tomentosum and S. sulfureum declined noticeably with increasing of plant biomass, indicating that allocation of aboveground biomass (AGB) and belowground biomass (BGB) were strongly influenced by plant size (biomass). The biomass pair AGB-BGB of S. fuhaiense showed an isometric effect (i.e. their allometric scaling exponents were 1.0), while the other two species showed allometric effect (the exponent< 1.0). The biomass pair AGB-LB of S. tomentosum and S. fuhaiense showed an isometric effect; whereas S. sulfureum fited the allometric relationship. The biomass pair LB-BGB of all the three species exhibited a common allometric scaling exponent (0.816), showing a strong functional convergence. In conclusion, there was no consistency between allocation pattern and allometric relationship in three Sterigmostemum species, but it represented the biomass allocation characteristics of ephemeroid plants. |