That knotweed the other day was chasmogamous. That simply means it has petals and shows them off. Of course, knotweed petals are not quite as showy as a rose, which might be the most famous show-off of all when it comes to petals. This trait is certainly a convincing argument that knotweed was once more active in attracting pollen from other individuals. Japanese rose is successful enough to have gotten transported to Michigan. That does show the advantage of this form of propagation. Japanese rose has been seen in AK, CT, DE, IL, MA, MD, ME, MI, MN, MO, NH, NJ, NY, OH, PA, RI, UT, VA, VT, WA, WI, WV, BC, NB, NF, NS, ON, PE, QC, and SPM. Japanese rose may be native in western Alaska. Lenawee Co MI, 6/20/11. Rose family, Rosaceae.