Poisonous and medicinal

An article about Canadian Yew, emphasizing its ironic mix of poisonous and medicinal properties, made me want to discuss similar flora and fauna found at my workplace.

First, the Canadian Yew, which might grow at my workplace, but I haven’t looked for it:


Found at the Wye Marsh is the Blue Flag Iris.

Although the rhizomes of blue flag are highly toxic, Aboriginal people have used the plant to alleviate a wide variety of ailments, including vomiting and constipation. The leaves have also been used for weaving baskets and mats, according to authors Doug Bennet and Tim Tiner in their book Up North Again.

(Caution: We do not recommend the use of these plants for medicinal or food purposes. Many plants are poisonous or harmful if eaten or used externally. The information on food and medicinal value is included only for interest. This information has been gathered from books and its accuracy has not been tested.)

My photos of the iris at the Marsh.

blue flag iris june 12 (20)

We also have massasauga rattlesnakes, although I have never seen a wild one.  In our display hall are two and this week a man from The Toronto Zoo came to the marsh and inspected them.  It was a thrilling time and I apologize for the blurry images: flash photography that might distract the handlers seemed inappropriate.

rattlesnake inspection (1) rattlesnake inspection (2)

The snakes were set on the floor and annoyed so that they tried to escape through a tube.  Once in the tube, and unable to bite, they were picked up and examined.  This happens once or twice a year.

From the US Fish and Wildlife service:

…rattlesnake venom has been explored for human medicinal use, including treatments for arthritis, MS, and polio. Rattlesnake venom also has anti-coagulant properties that stay localized, unlike coumadin and some other anti-coagulants that are currently used to prevent strokes and heart attacks.

My university has prepared an extensive bibliography on the massasauaga.

Having learned of medicinal uses for these organisms, I had to expand my search. To my surprise, poison ivy also has some medicinal value.  From Botanical.com:

The fluid extract, prepared from the fresh leaves, is mostly given in the form of a tincture, in doses of 5 to 30 drops. In small doses it is an excellent sedative to the nervous system, but must be given with care, as internally it may cause gastric intestinal irritation, drowsiness, stupor and delirium.

It has been recommended in cases of incontinence of urine. For this, the bark of the root of R. aromatica is also employed very successfully, an infusion of 1 OZ. to a pint of boiling water being taken in wineglassful doses.

The fluid extract of R. Toxicodendron can be used as a vesicant or blister producer, like cantharides, mezeron, and oil of Mustard.

The best preparation is a concentrated alcoholic tincture made from the green plant in the strength of 1 in 4. The dose of 25 per cent tincture is given in 1 to 5 drops three times a day. A solid extract is not used owing to the extreme volatility of the active principles of the crude drug.

Its milky juice is also used as an indelible ink for marking linen, and as an ingredient of liquid dressings or varnishes for finishing boots or shoes, though R. venenata is more extensively used for the latter purpose.

As botanical.com describes homeopathic usage, I was uncertain of how much I should trust it as a resource.  Web MD, far more briefly, confirms their claims, however.

Updated before posting: Now I do have some good poison ivy photos.  Ironically, I currently have no personal image of poison ivy so let me show a similar plant that I want assistance in identifying. The stalks look wrong and the leaf serrations are not deep enough in my opinion.

not poison ivy

Now for the poison ivy:

ivy and trillium (2)

I like this photo and location as I can show students two different three-leaved plants.  Here are trilliums and poison ivy.  The ivy has pointy leaves with some serrations.  It’s counter-intuitive that the trilliums show no sign of predation but the poison ivy does. The only animal that I know is affected by poison ivy is humans.  As I tell students, your dog or cat might walk through the bushes unaware then spread the oils to you when you pick it up.

Spotted water hemlock, as Web MD states, is quite poisonous and warns that there is insufficient evidence for medicinal use:

Insufficient Evidence for:

  • Migraine headaches.
  • Painful menstrual periods.
  • Intestinal worms.
  • Skin redness and swelling (inflammation), when applied to the affected area.
  • Other conditions.

More evidence is needed to rate the effectiveness of water hemlock for these uses.

I have not seen it on site, but am told specimens have been removed.

Added two days later: Bittersweet Nightshade.  Apologies for the terrible photo – the camera battery was dying and I rushed the shot.

overnight jun 24-25 (7)


For better images and info, the Wikipedia entry is here

An excerpt:

The alkaloids, solanine (from unripe fruits), solasodine (from flowers) and beta-solamarine (from roots) inhibited the growth ofE. coli and S. aureus.[8] Solanine and solasodine extracted from Solanum dulcamara showed antidermatophytic activity against Chrysosporium indicum, Trichophyton mentagrophytes and T. simil. and thus may cure ringworm.[9]

Although fatal human poisonings are rare, several cases have been documented. The poison is believed to be solanine.


Not entirely unrelated: Why are wetlands so important to preserve?

 The EPA points out that, besides containing a disproportionately high number of plant and animal species compared to other land forms, wetlands serve a variety of ecological services including feeding downstream waters, trapping floodwaters, recharging groundwater supplies, removing pollution and providing fish and wildlife habitat.




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