After six family members, who ate stew at a Gaithersburg home began exhibiting a variety of symptoms, including convulsions, heart palpitations and hallucinations, investigators believe a plant called Datura stramonium, also known as jimsonweed, is to blame.

"Hallucination, they didn't know what they were doing, what they were saying, they were just not in their senses," relative Satnam Singh said.

The family's grandmother grows her own herbs in the front yard, and investigators suspected that something she picked there was responsible for the poisoning. It was initially believed that the only thing from the yard added to the stew was ordinary mint, so investigators hypothesized that a chemical on the herbs, like a pesticide, was responsible for the illness.

It was reported early Friday that the investigation had discovered what they believe to be jimsonweed in the family's yard, right next to an herb garden. Jimsonweed can cause illness and is sometimes used recreationally for its hallucinogenic properties.

The county health department took a botanist to the family's backyard, where the plant expert immediately focused on the wild jimsonweed growing near the herbs. "It's wild in the state of Maryland so everyone could have it in their yards," said Carol Jordan, Communicable Disease and Epidemiology Director.

Jordan said the plant, which causes digestive and neurological problems, grows to five feet tall, but in early stages, it's about the height of herbs. "Just don't ingest something you don't know. That would be the public health message."

The fire department reports being called around 1:00 am to the Gaithersburg residence , where they found all six people with a variety of symptoms. A hazardous materials team was called to the scene, but determined that the culprit was not a carbon monoxide leak or other standard chemical exposure, but rather an ingredient in a stew eaten by all of the sick people.

"We're pretty confident it was the stew. The more they ate, the worse off they were," said Pete Piringer with Montgomery County (web|news) EMS.

Dr. Gaurov Dayal, Shady Grove Adventist Chief Medical Officer, said residents should be careful, "If it's something you've grown in your yard you should absolutely wash it, and for that matter wash any fruit or vegetables."

Patient privacy rules prevent the doctor from saying more about the victim's specific treatment. All six of the sick people are adults, ranging in age from 20 to 70 years old, and though their illness is not thought to be life-threatening, five of the six are still in intensive care in stable condition. It's been reported people who consume large amounts of jimsonweed can overdose and die from the drug.