Marsh Smartweed

I had trouble trying to identify this plant, as it looked so much like Water Smartweed. However, this plant that I came across yesterday was growing on land near the edge of a wetland, has hairy leaves. I eventually found the following information on the Internet and forgot to note which website (it WAS around 3:00 a.m.!!).

"When the amphibious Water Persicaria (P. amphibium) lifts its short, dense, rose-colored ovoid or oblong club of bloom above ponds and lakes, it is sufficiently protected from crawling pilferers, of course, by the water in which it grows. But suppose the pond dries up and the plant is left on dry ground, what then ? Now, a remarkable thing happens: protective glandular, sticky hairs appear on the epidermis of the leaves and stems, which were perfectly smooth when the flowers grew in water. Such small wing-less insects as might pilfer nectar without bringing to their hostess any pollen from other blossoms are held as fast as on bird-lime. The stem, which sometimes floats, sometimes is immersed, may attain a length of twenty feet ; the rounded, elliptic, petioled leaves may be four inches long or only half that size. From Quebec to New jersey, and westward to the Pacific, the solitary, showy in-florescence, which does well to attain a height of an inch, may be found during July and August. "