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L-donax growth model.
Photo taken from the virtual growth model of the invasive weed species Arundo donax, constructed using L-systems modeling.

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Animation of "Giant Reed" Plant May Speed Its Demise

By Marcia Wood
August 19 2009

Along streams and irrigation canals in 16 states, a wily weed called giant reed, or Arundo donax, can grow a remarkable 3 to 6 inches a day. This intruder crowds out native plants like cottonwoods and willows, and can block water flow to farms and cities.

In research designed to stop arundo's advance, Agricultural Research Service (ARS) ecologist David F. Spencer and co-investigators have developed a computerized, science-based animation that shows precisely how a real-world arundo plant grows. The animation—apparently a first for an invasive weed—is intended for researchers, streamkeepers, students and others.

During this brief clip, a reality based "virtual arundo" goes through its first year of growth, emerging from a single, thick, underground stem, or rhizome, to reach its maximum height of about 30 feet.

The animation is derived from studies led by Spencer. In some of those studies, thousands of digitized measurements were taken by magnetic sensors of dozens of arundo plants. Using commercially available software, the measurements were analyzed to create L-DONAX, a computer-based model of arundo's growth, with optional 3-D animation.

Work to improve the first (2007) version continues. Meanwhile, the animation has been newly posted on the web. 

Researchers can use L-DONAX and its animations to gauge—and see on-screen—the predicted effects of tactics to control arundo. For example, the model could help scientists determine the best times in the weed's growth to unleash helpful insects that attack arundo's leaves, stems or rhizomes.

Spencer, who works at the ARS Exotic and Invasive Weeds Research Unit in Davis, Calif., created L-DONAX with David Thornby, formerly at the University of California-Davis; Jim Hanan of the University of Queensland, Australia; and Anna Sher of the University of Denver and Denver Botanic Garden in Colorado.

ARS, the U.S. Department of Agriculture's principal intramural scientific research agency, and the Australian Research Council, Canberra, funded the research.