Re: What's this that popped up?
Only the lower leaves have the typical 3- or 5-lobed hemp-type leaves, which are in opposite pairs ; the upper leaves are just single oval in opposite pairs. All leaves are oval, pointed and toothed and similar to those of Hemp (Cannabis sativa), hence the name.
No relation to : Agrimony [a plant with similar name]. Nor is it, despite the name, related to Hemp nor to Cannabis, which refers more to the shape and pattern of the leaves than to any psychotropic substances. Nor to Bifid Hemp-Nettle, Common Hemp-Nettle, Large-Flowered Hemp-Nettle or Red Hemp-Nettle since Hemp-nettles belong to the Mint and Dead-nettle Family.
Grows beside freshwater such as streams, canals, fens and in damp woods. Sometimes in drier places.
Uniquely identifiable characteristics
Distinguishing Feature : The leaves in opposite pairs of three with the umbel of pinkish-red flowers atop.
Hemp-agrimony is a hemicryptophyte, meaning the flower buds start off on or near the soil surface like they do in Dandelion. Like Dandelion, the seeds are borne by the wind on a pappus, or parachute.