Poison Hemlock

Appearance

"Conium maculatum" is a herbaceous biennial flowering plant that grows to 1.5–2.5 m tall, with a smooth, green, hollow stem, usually spotted or streaked with red or purple on the lower half of the stem. All parts of the plant are hairless; the leaves are two- to four-pinnate, finely divided and lacy, overall triangular in shape, up to 50 cm long and 40 cm broad.

Hemlock's flower is small and white; they are loosely clustered and each flower has five petals. The plant looks like the wild carrot plant. One can distinguish the two from each other by hemlock's smooth texture, mid-green, quite vivid, color and typical height of large clumps being least 1.5 metres, twice the maximum of wild carrot. Carrots have hairy stems that lack the purple blotches. It can be confused with harmless cow parsley.

Naming

Vernacular names in the English language are poison hemlock, poison parsley, spotted corobane, carrot fern, devil's bread or devil's porridge

The plant should not be visually confused with the North American-native "Tsuga", a coniferous tree sometimes called the hemlock, hemlock fir or hemlock spruce, from a slight similarity in the leaf smell. The ambiguous shorthand of 'hemlock' for this tree is more common in the US dialect than the plant it is actually named after.

Similarly, the plant should not be confused with "Cicuta".

Wild poison hemlock also can be confused for Queen Anne's lace, which is wild or feral carrot plants and sometimes gathered and eaten as an edible wildflower. The authentic, edible plant lacks the purple mottling of hemlock on its stems, which in the case of Queen Anne's lace are also more hairy.

Distribution

The hemlock plant is native to Europe and the Mediterranean region.

It exists in some woodland in most British Isles counties; in Ulster these are particularly Down, Antrim and Londonderry.

It has become naturalised in Asia, North America, Australia and New Zealand. It is sometimes encountered around rivers in southeast Australia and Tasmania.

It is an introduced species in 12 U.S. states.

Habitat

The plant is often found in poorly drained soil, particularly near streams, ditches and other watery surfaces. It also appears on roadsides, edges of cultivated fields, and waste areas "Conium maculatum" grows in quite damp soil, but also on drier rough grassland, roadsides and disturbed ground. It is used as a food plant by the larvae of some lepidoptera, including silver-ground carpet moths and particularly the poison hemlock moth. The latter has been widely used as a biological control agent for the plant. Poison hemlock grows in the spring, when much undergrowth is not in flower and may not be in leaf. All plant parts are poisonous.

Defense

Poison hemlock contains coniine and some similar poisonous alkaloids, and is poisonous to all mammals that eat it. Intoxication has been reported in cattle, pigs, sheep, goats, donkeys, rabbits, and horses. Ingesting more than 150-300 mg of coniine, approximately equivalent to six to eight hemlock leaves, can be fatal for adult humans. The seeds and roots are also toxic, more so than the leaves. While hemlock toxicity primarily results from consumption, poisoning can also result from inhalation, and from skin contact. better source needed Farmers also need to be careful that the hay fed to animals does not contain hemlock. Poison hemlock is most poisonous in the spring when the concentration of γ-coniceine is at its peak.

Poison hemlock grows quite tall, reaching heights of up to twelve feet. The stalk of hemlock is green with purple spots and completely lacks hair. A biennial plant, hemlock produces leaves at its base the first year but no flowers. In its second year it produces white flowers in umbrella shaped clusters. Hemlock can be confused with the wild carrot plant; however, the wild carrot plant has a hairy stem without purple markings, grows less than three feet tall, and does not have clustered flowers.