Abstract: Annuals are an important component of herbaceous layer in summer and autumn in the Gurbantunggut Desert, China. In this study, four annuals (Salsola ruthenica Iljin, Agriophyllum squarrosum L. Moq., Ceratocarpus arenarius L., and Horaninowia ulicina Fisch. et Mey.) in Chenopodiaceae were chosen as targets, and the modular morphology, biomass allocation and their allometric relationships were comparatively analyzed. The results indicated that A. squarrosum had the biggest body size (volume and biomass), followed by S. ruthenica, and C. arenarius and S. pycnophylla were the smallest. S. pycnophylla had the highest ratio of root to shoot biomass (R/S), followed by S. ruthenica, and A. squarrosum and C. arenarius were the lowest. There were significant positive correlations between modular morphology and biomass, indicating a strong tendency of collaborative change. R/S showed negative correlations between most morphological variables and biomass, indicating that the allocation ratio of belowground biomass decreased gradually with the increase of plant size. Most of the modular morphology and biomass indices represented significant allometric relationships with the scaling exponent <1.0, but most of the allometric scaling exponents among the four annuals were not different and these species all had the common scaling exponent each. This result revealed that although the plant sizes of the four species varied, the four annuals had the same growth ratio and collaborative change characteristics among these modular morphology and biomass indices, reflecting the convergent adaptation of different species in the lifeform ‘annuals’ to arid deserts.

Key words: cold resistance, Carex, semi-lethal temperature, physiological response