The Clero bungei (Cashmere Bouquet) doesn't set seed either but it sure produces hundreds of runners that travel underground and come up anywhere and everywhere! Our deck runs the entire length of the back of the house, is 12 feet wide/deep and those danged things pop up through the wood slats all the way up against the house! It amazes me that they would grow beneath a dark, dark wooden deck like they do ... beautiful, tough plant but a shame it has to be such a pest.
