Water hemlock has small, white flowers that grow in umbrellalike clusters. Side veins of the leaves lead to notches, not to tips at the outer margin.
The thick rootstalk contains a number of small chambers. These hold a highly poisonous brown or straw-colored liquid that is released when the stem is broken or split. Everything that the liquid touches becomes a potential source of poisoning for livestock. Thick, fleshy tubers and slender individual roots grow from the bottom of the rootstalk.
Water hemlock is probably the most poisonous plant that grows in the United States. Only a small amount of the toxic substance is needed to produce poisoning in livestock-
or in men. Water hemlock may be confused with poison hemlock because of the similarity in names. However, these two are different plants that cause different types of poisoning.
In cases of water hemlock poisoning in man, induce vomiting immediately. Call a physician.
Animals seldom eat water hemlock if good forage is available. Most losses occur in early spring or after the plants have been sprayed with 2,4-D.
The underground portions of the plant, especially the tuberous roots, are very dangerous. Severe livestock losses may occur when the roots become exposed and are eaten by the animals. People are sometimes poisoned by eating the roots, which they mistake for wild parsnips.
The toxic substance in the plant is cicutoxin, a highly poisonous unsaturated alcohol that has a strong carrotlike odor. It is found principally in the roots, but it is also present in the leaves and stems during early growth. Leaves and stems lose most of their toxicity as they mature.
Where and When It Grows
Water hemlock, a wetland plant, is commonly found in wet meadows and pastures along the banks of streams. It starts growth in the spring. In the higher elevations, the hemlock flowers in June or July.
How It Affects Livestock
Livestock usually show signs of poisoning 1 to 6 hours after they eat the plant; they may die within 1 to 2 hours after signs appear.
Signs of poisoning
1. Muscle twitching
2. Rapid pulse
3. Rapid breathing
6. Dilation of the pupils
7. Excessive salivation
8. Frothing at the mouth
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