Foliar water uptake improves branch water potential and photosynthetic capacity in Calligonum mongolicum

•The glabrous assimilating branch of xerophytes can absorb atmospheric water resources.•The water taken up by the branches could be transported downward through the xylem.•The uptake of atmospheric water mitigated the drought stress in Calligonum mongolicum.•Foliar water uptake improved the photosynthetic capacity in Calligonum mongolicum.