text: what's and how deadly is hemlock? how much do you need for it to kill you?  where can you get it? what the death rate? how do you died from it? and how long does it take for you to die from it? conium maculatum (hemlock or poison hemlock), the most common of several species of hemlock noted for their toxicity. contains the alkaloids coniine, n-methylconiine, conhydrine, pseudoconhydrine and g-coniceïne. the most important and toxic of these is coniine. coniine is a neurotoxin, which disrupts the workings of the central nervous system and is toxic to people and all classes of livestock.conium maculatum has been introduced and naturalised in many other areas, including much of asia, north america and australia. poison hemlock is often found on poorly drained soils, particularly near streams, ditches, and other surface water.