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.
Hemp-agrimony contain the poisons Euparin, some sesquiterpene lactones including Eupatoriopicrin and several Pyrrolizidine Alkaloids such as the non-toxic
Cynaustraline plus the toxic PA's: Supinine, Amabiline, Lycopsamine, Echinatine, Intermedine and
Rinderine. Euparin is a benzofuran or benzopyran which is phytotoxic and inhibits electron transfer in chloroplasts, which suggests that the plant has some internal use for it.
Viridiflorine and Cynaustraline are stereoisomers of each other, the difference between the two only being the position of the H-atom on the squiggly bond; whether it is above or below the plane of the pyrrolizidine rings. It differs from Amabiline only in the lack of a hydroxyl group on the pyrrolizidine rings and in an =O instead of a CH2. Both Viridiflorine and Cynaustraline are non-toxic. However, both Amabiline and Rinderine are.
All parts of the plant are poisonous, ingestion of which results in tremor, delirium and death. Pyrrolizidine Alkaloids will alkylate DNA molecules, and are therefore mutagenic and carcinogenic.