What kind of poison was used in "The Name of the Rose"?

In the novel "The Name of the Rose" by Umberto Eco, a fanatical monk laced the pages of a book with a poison, which led to the death of several monks in a medieval monastery. Based on modern toxicological knowledge, an attempt can be made to determine whether there exists a substance meeting the criteria of the poison described in the novel. To this end, toxicological literature on the lethal doses of plant-derived poisons and their duration of action was reviewed. Cowbane (Cicuta virosa), a plant used for preparing poisonous potions, contains cicutoxin which kills at a dose of 500 mg. Similar toxicity is displayed by water dropwort (Oenanthe crocata) and Cerbera odollam growing in India and Madagascar. Hemlock (Conium maculatum) contains coniine which is able to kill a victim after exposure to a dose as low as 100 to 200 mg. Morphine found in opium poppy (Papaver somniferum) and colchicine contained in autumn crocus (Colchicum autumnale) produce lethal effects at similar doses. So do more exotic plants such as Calabar bean (Physostigma venenosum) which contains physostygmine. Two other exotic plants that need to be mentioned in this context are far more poisonous. They include Saint Ignatius's bean (Strychnos ignatii) and strychnine tree (Strychnos nux-vomica). Both contain strychnine, the lethal dose of which is 30 mg. Death cap (Amanita phalloides) might also be considered in this context, but despite being lethal at a dose of 20 mg, amanitin contained in this fungus takes a few days to kill a victim, so the effect is considerably slower than that experienced by the monks in Eco's novel. A dose of 10 mg is sufficient to kill a human with any of four other plant-derived poisons: antiarin, atropine, digoxin and strophantin. Aconitum (Aconitum napellus), also known as monkshood, contains aconitine and is an even more deadly plant, with the lethal dose for humans being only 2 mg. Ricin and abrin are ranked even higher in the list of plant-derived toxins, as they are able to kill in doses lower than 1 mg. However, they could not have been used by the murderer in "The Name of the Rose", as they cause death only several days after ingestion. To conclude, the plant that best matches the criteria mentioned in the novel is Aconitum.