Dangerous Plants

It’s summer and a wonderful time for hiking in fields and forests, observing the plants and animals that live here.  But as you are out enjoying nature, there are dangerous plants to be aware of.  Some species can also be found in backyard gardens where they may pose a hazard to people and pets.  Here are three to avoid.

Poison hemlock, Conium maculatum, is native to Europe and North Africa but is widely distributed in North America.  The plant can grow to 12′ tall on a hollow, hairy stem, green with dark maroon spots.  Flowers form a small, loose, white cluster often mistaken for Queen Anne’s Lace.  All parts of the plant, especially the seeds and roots, contain a poisonous alkaloid oil called coniine.  When ingested, the oil works as an inhibitor directly on the central nervous system which may lead to failure of the respiratory muscles and death.  Eating six to eight leaves may prove fatal for humans.  If the oil comes in contact with skin exposed to direct sunlight, a phytophotodermatitis reaction occurs causing severe burns of the area.

Deadly nightshade, Atropa belladonna, another plant introduced to the U.S., has a long history of use in medicine, cosmetics and as a toxin.  Plants grow to seven feet tall with purple and green, lightly scented, bell-shaped flowers.  All parts of the plant, but most especially the root, contain tropane alkaloids having anticholinergic properties inhibiting the involuntary muscle movements the body depends on for functions including sweating, breathing, and heart rate.  The berries are attractive, dark red, cherry-like and sweet tasting.  Consumption of 2-5 berries by children and 10-20 berries by adults can be fatal.  Only cattle and rabbits seem to have no reaction to the plant’s poison.

Giant hogweed, Heracleum mantegazzianum, a member of the carrot family, is native to Eurasia and was introduced to the U.S. as an ornamental in the late 19th century.  This plant typically grows 6′ to 18′ tall with 3′-5′ diameter, deeply-lobed leaves.  Stems are bright green with purple splashes and coarse white hairs.  Greenish-white flowers, similar to Queen Anne’s Lace produce 10,000 to 50,000 half-inch long seeds per plant.  Like poison hemlock, the sap causes a phytophotodermatitis reaction when in contact with skin subsequently exposed to the sun’s UV rays.  Initial reactions may be mild including red, itchy skin developing into more severe blisters and burns after 24-48 hours.  Scars last several years, and hospitalization for burn treatment is not uncommon.

All three species are considered weeds, found in fields and along forest edges, and may not be actively controlled or removed resulting in widespread distribution.  Recently, poison hemlock has become a serious backyard problem in Ohio and Indiana where plants have been spreading rapidly.  Causes for the spread are not clear, but the trend is continuing to move westward.  Enjoy your nature viewing, but be aware of the plants around you and the secrets they may hold.