XVI International Botanical Congess

Polygonum cuspidatum or Japanese Knotweed, introduced and widespread in the eastern United States, shows aggressive colonization in streams, stream banks, moist disturbed areas and even in paved street crevices. Individual plants commonly reach heights of 200 cm with growth rates of 2 cm/day until flowering. Dry weight increases of 207% or 1.44 gm/day per plant were recorded over a 30- day period in an intermittent stream population with a low shoot/leaf ratio of 1.15. Experimental shoot cuttings indicated a 70% successful adventitious root development within 14 days of stems harvested prior to floral bud development compared to a 20% rooting potential in shoots developing flowers and indicates a means of rapid colonization in aquatic habitats. Rooting activity of pre-flowering stem cuttings was examined for possible correlatlion with auxin levels.