The poison hemlock (Conium maculatum L.) is a dangerous plant that grows throughout the United States.The hemlock plant has white flowers that grow in … Poison hemlock (Conium maculatum) is a poisonous invasive weed that has caused many accidental deaths because of its resemblance to carrots, including the wild carrot (Queen Anne’s lace). These types of flowers are common in the carrot family and are similar to wild carrot (also known as Queen Anne’s lace, Daucus carota ), which is often mistaken for this plant at younger stages. Where Does Poison Hemlock Grow? The amount of toxin varies and tends to be higher in sunny areas. Poison-hemlock is acutely toxic to people and animals, with symptoms appearing 20 minutes to three hours after ingestion. All parts of the plant contain the poisonous alkaloid coniine and are toxic to Eating the plant is the main danger, but it is also toxic to the skin and respiratory system. The poisonous agents in the plant are volatile alkaloids, and they are found in every part of the plant. Poison-hemlock is sometimes confused with western water hemlock, a more deadly species, because the names are similar. Poison hemlock commonly grows along roadsides, at field edges, and in low-lying areas, near creeks and streams. What is poison hemlock? Poison hemlock is native to Europe and North Africa and has been introduced to Asia, North America, and Australia. Overview Information Hemlock is a very poisonous plant. In fact, all parts of the plant are toxic. Poison hemlock is a biennial that forms a rosette its first year, often going unnoticed, and then produces white umbel flowers (umbrella-like) on tall stems in the spring-summer of its second year. Poison hemlock is a biennial, which means it takes two years for it to flower and go to seed. Poison hemlock ( Conium maculatum) is native to Europe and North Africa, but has widely naturalized in many other areas. During the first year, it germinates and grows as a rosette, a low cluster of leaves along the ground. All parts of the plant are poisonous and even the dead canes remain toxic for up to three years. Poison hemlock, (Conium maculatum), poisonous herbaceous plant of the parsley family (Apiaceae). Historically hemlock was used in ancient Greece to poison condemned prisoners, and it was what killed Socrates after he drank a potent hemlock infusion. Poison-hemlock is commonly called deadly hemlock, poison parsley, spotted hemlock, European hemlock, and California or Nebraska fern. Poison-hemlock has white flowers that grow in small erect clusters.