Ayup IAWAet al. –Journal Hydraulic 36 (1),traits 2015: of desert 69–83 plants 69 XYLEM ANATOMY AND HYDRAULIC TRAITS OF TWO CO-OCCURRING RIPARIAN DESERT PLANTS Mubarek Ayup1,2,*, Ya-Ning Chen1,2, Maina John Nyongesah3, Yuan-Ming Zhang1, Vishnu Dayal Rajput1,2 and Cheng-Gang Zhu1,2 1Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China 2State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China 3School of Biological Sciences, Jaramogi Oginga Odinga University of Science and Technology, 210-40601 Bondo, Kenya *Corresponding author; e-mail:
[email protected] ABSTRACT Populus euphratica Oliv. and Tamarix ramosissima Ledeb. are the dominant riparian plants in desert ecosystems in China, where they play a significant role in maintaining ecological balance. To obtain a better insight into the ecological adaptations of xylem structure and hydraulic traits in desert phreatophytes to extremely drought-stressed environments, we investigated various quantitative features of the vessels and intervessel pits, as well as the xylem hydraulic ef- ficiency (KS(MAX)) and native embolism rate (PLC, %), in the woody shoots and lateral roots (all c. 2–4.5 mm in diameter) of P. euphratica and T. ramosissima from natural populations in the Heihe River Basin, northwestern China. The relationships between xylem anatomy and hydraulic traits are also discussed. There were significant anatomical differences between lateral root and woody shoot xylem within individual species. For lateral roots , arithmetic, hydraulic and maximum vessel diameter (D, DH, DMAX), average vessel area (VA), interves- sel wall thickness (TVW), intervessel pit membrane and pit aperture areas (APM, APA), and intervessel pit membrane and pit aperture diameters (DPM, DPA), were larger than in woody shoots (P < 0.05).The mean KS(MAX) values in lateral roots were 6–11 times greater than in woody shoots for P.