There are over 624 threatened or endangered plants in Pennsylvania as of 2010, according to the United States Department of Agriculture. Many of these contain some form of poison that is highly toxic to humans. Some of the most beautiful plants can be very dangerous to humans. Never eat an unfamiliar plant.
The dwarf azalea is a perennial shrub with purple flowers that is listed as an endangered plant in Pennsylvania by the United States Department of Agriculture. Its dark green foliage contains grayanotoxins that, if ingested, can cause a burning or tingling sensation in the mouth that leads to numbness. After two hours, these symptoms turn into nausea, vomiting, confusion, sweating and slowing of the pulse. The chance of seizures is high if large quantities of leaves have been consumed. Just a couple of the leaves cause distress to the human body.
Smallflower False Foxglove
The smallflower false foxglove is an annual herb that has purplish rose blossoms. It contains cardiac glycoside, which is known to change the heart's rate. This slim, narrow plant has many branches and is an ingredient for many heart medications, and should never be consumed. Visible symptoms of ingestion include dizziness, headache, confusion, vomiting or stomach cramps. Blood pressure and heart fluctuations will occur if left untreated.
The tall larkspur is a perennial herb that grows violet-blue or white flowers in Pennsylvania’s forests and mountain slopes. It grows to 2 to 6 feet and has spike-shaped, divided leaves. It is very toxic even as a seedling, and can cause depression, stomach pain, nervous excitement and even death. Its seeds are also dangerous if consumed.
Slender Blue Iris
The slender blue iris is a perennial flowering herb that flourishes with blue blossoms with yellow and white markings. It grows to 1 to 3 feet tall and has narrow green basal leaves. Its underground stems are toxic and can cause unrelenting stomach upset.