From the CO2science.org archive: This plant’s Latin name is Polygonum lapathifolium L., but also Persicaria lapathifolia. And in English it has even more names, including Curlytop Knotweed, plus Dock-leaved smartweed, Large-leaved smartweed, Bitter smartweed, Pale smartweed, Willow weed, Nodding Smartweed, and probably others we didn’t find. It also has medicinal value as a stomach remedy, which apparently has been known a long time since it was found in the stomach contents of Tollund Man, a mummified corpse of a guy who lived 2,000 years ago in Scandinavia. Whatever you call it, and whether you plan to ingest it or merely admire its pretty pink flowers, it has a promising future as our CO2 levels keep rising. In 1995 and 2007 there were five experiments showing an additional 300 ppm CO2 boosted its growth an average of 19.4 percent.