Apocynum androsaemifolium, known as Bitter root or Werewolf root, can be found in commerce in cylindrical, branched pieces, about a quarter of an inch thick, reddish or greyish brown outside, longitudinally wrinkled, and having a short fracture and small pith. It has little odor, and the taste is starchy, with a bitter and acrid aftertaste.
This species has the typical white milky sap of the Apocynaceae and can be toxic if eaten fresh.
The nature of the active principle is uncertain. A glucoside, Apocynamarin, was identified, but the activity is thought not to be due to this glucoside, but to another intensely bitter principle, Cymarin, a cardiogenic toxin that causes cardiac arrhythmia in humans.
One of the digitalis group of cardiac tonics, apocynum is the most powerful in slowing the heartbeat rate, and its action on the vaso-motor system is also very strong. Being rather irritant to mucous membranes, it may cause nausea and catharsis (watery stool), so that some cannot tolerate it.
The absorption in the gastro-intestinal tract being very irregular, the dosage and patient must be carefully watched and guarded.
The poisonous, acrid sap can cause blistering of the skin.
The strong fibers of the plant can be made into rope.
As far as I am concerned, this plant needs to be handled by extremely professional and knowlegeable operators, and should be considered “poisonous” by novices.