Hemlock, Conium maculatum, is a tall, foetid, biennial herb of the family Umbelliferae (commonly known as the carrot family). Stems of flowering plants are 3–6 ft tall, branched, furrowed, hollow, and usually purple-flecked or spotted. The carrotlike, finely-divided leaves are on long, hollow, purple-spotted stalks. Masses of small white flowers are borne in umbels. Hemlock is abundant throughout New Zealand and is mostly found in waste places, on roadsides and banks of streams, in shaded places, and frequently in home gardens.
Hemlock was recognised as poisonous in earliest times and is not only associated with the death of Socrates, but also with animal poisonings, and, in particular, poisonings in children. Children, who do not seem deterred by its unpleasant mousy-smell, are known to use the hollow stems as “pea shooters” or whistles, to mistake the leaves for parsley, to chew the seeds, and, in at least one case, to use hemlock as make-believe vegetables. The whole of the plant, including the parsnip-like taproot, is poisonous, the seeds being especially so.
Toxic volatile alkaloids are present throughout the plant and produce in man the well-known symptoms of general and gradual weakening of muscular power, and, in lethal doses, death results from gradual paralysis. Loss of sight may occur.
All classes of livestock have been poisoned by hemlock and it is thought that these poisonings are more frequent in the spring.
by Henry Eamonn Connor, M.SC., Botany Division, Department of Scientific and Industrial Research, Lincoln.