Conium, or poison hemlock (_Conium maculatum_), is a large, poisonous
European biennial plant of the parsley family, naturalized in the
Northeastern States and in California. The full-grown but unripe seeds
(fruits) and the leaves are used medicinally.
Conium is easily grown, and has been found to thrive in both
comparatively moist clay soil and in dry sandy loam. In rich, moist
land it may easily become a troublesome weed. Conium grows readily
from seed, which may be sown either in the fall or early in the spring
in drills 2 or more feet apart. As soon as the seedlings can be
distinguished in the row, cultivation similar to that given ordinary
garden crops is begun. The plants usually blossom in the second year,
and when the oldest seeds are full grown but still green in color the
plants are harvested and the seed at once thrashed out and dried with
the least possible exposure to the light. The small and undeveloped
seed should be screened out and rejected and the good seed stored in
containers that will exclude light and air. The leaves are collected
when the plant is in flower, quickly dried in the sun, and stored in
the same manner as the seed.
Estimated yields at the rate of 600 to 800 pounds of seed per acre have
been obtained, but the yield is very uncertain, since the flowering
plants are especially subject to the attacks of insects which destroy
the crop of seed. The prewar prices as quoted in the wholesale drug
markets ranged from 5 to 10 cents a pound for the seed and 5 to 6 cents
for the leaves. The prices in June, 1920, for the seed were 35 to 36
cents, and for the leaves 25 to 26 cents a pound.