Hemlock - Conium maculatum
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Poison hemlock is a stout to slender biennial, up to 3 m tall, from an
unbranched taproot. The stems are glabrous, glaucous and usually purple
spotted. The leaves are broadly ovate in outline, 1-3 dm long, 3-4 times
pinnately compound with sheathing petioles. The leaflets are ovate-oblong,
4-10 mm long, toothed or incised. The small white flowers are borne in
compound umbels. Fruits are brown, broadly ovoid with prominent undulate
Poison hemlock is very similar to the related species, water hemlock
(Cicuta maculata). They can be distinguished by their roots and leaves.
Poison hemlock has a long, unbranched, white, fleshy, taproot compared
to the root system of water hemlock which is composed of several tubers.
The leaf veins of poison hemlock run to the tips of the teeth while those
of water hemlock run to the notches between the teeth. Poison hemlock
can be found along roadsides, streambanks, ditches, canals, thickets,
meadows, and low waste places.
All parts of the plant are poisonous. Symptoms include loss of appetite,
excessive salivation, bloating, and a rapid but feeble pulse. Animals
may also experience muscle incoordination and appear to have great abdominal
pain. Many cases of human poisoning occur because the roots are mistaken
for parsnips, the leaves for parsley, and the root and seeds for anise.
Links to more information
Website, video, and graphics by Rob Nelson
For more information on this plant or management please contact US Army Corp of Engineers