The intra- and inter-specific variations in net photosynthetic (PN) and transpiration (E) rates and water use efficiency (WUE) of Puccinellia tenuiflora and Puccinellia chinampoensis leaves were compared. The two species experienced a similar habitat, but differed in leaf area, leaf colour, and nitrogen contents. Leaf PN and E for both reproductive and vegetative shoots of the two species declined with leaf age. PN for reproductive shoots was less than for vegetative shoots, but their E was greater than that of vegetative shoots in the dry season. The average PN and E for reproductive shoots of P. tenuiflora were lower than those of P. chinampoensis, but higher for vegetative shoots. and R. Z. Wang, Y. Q. Yuan.