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This study investigated the absorption of arsenic (As), sulfur (S), and phosphorus (P) in the desert plant Chilopsis linearis (Desert willow). A comparison between an inbred line (red flowered) and wild type (white flowered) plants was performed to look for differential responses to As treatment. One month old seedlings were treated for 7 days with arsenate (AS(2)O(5), As-v) at 0. 20, and 40 mg As-v L-1. Results from the ICP-OES analysis showed that at 20 mg As-v L-1, red flowered plants had 280 +/- 11 and 98 +/- 7 mg As kg(-1) dry wt in roots and stems, respectively, while white flowered plants had 196 +/- 30 and 103 +/- 13 mg As kg(-1) dry wt for roots and stems. At this treatment level, the concentration of As in leaves was below detection limits for both plants. In red flowered plants treated with 40 mg As-v L-1, As was at 290 +/- 77 and 151 +/- 60 mg As kg(-1) in roots and stems, respectively, and not detected in leaves, whereas white flowered plants had 406 +/- 36, 213 +/- 12, and 177 +/- 40 mg As kg(-1) in roots, stems, and leaves. The concentration of S increased in all As treated plants, while the concentration of P decreased in roots and stems of both types of plants and in leaves of red flowered plants. X-ray absorption spectroscopy analyses demonstrated partial reduction of arsenate to arsenite in the form of As-(SX)(3) species in both types of plants. (C) 2009 Elsevier Ltd. All rights reserved.