Abstract: Longdistance dispersal of seed by wind is usually considered to be important for the evolutional processes of plant species. The settlement velocity of a wind-dispersed seed is a major component of its dispersal ability. In this paper, the seed settlement velocity of five weed species with pappus was studied under the laboratory conditions without the influence of wind or air currents. The seeds ofSolidago canadensis, Aster tataricus, Conyza canadensis, Phragmites communis and Lagedium sibiricum were freely released from the heights of 0.5, 1.0, 1.5 and 2.0 m, and their settlement time from each height was recorded. The results indicated that the seed settlement velocity of the weed species was 14.1, 20.4, 20.8, 23.3 and 33.3 cm·s^-1, respectively. Among the test weed species, S. canadensis had the slowest seed settlement velocity, and thus, was more suitable for long-distance wind dispersal.

Key words: Cyperus alternifolius, Coleus blumei, Jasminum sambac, Floating phytoremediation system, Eutrophic wastewater, Purification