The Wood Folk Diaries: Volume 4 (Poisonous Plants), Chapter 4: Blue Flag Iris

Table of Contents

Dear Wood Folk,

We’ve covered a tinier iris before: blue-eyed grass. It’s a miniature lookalike you might find in your lawn around cottage country Ontario. Our title iris on the other hand can grow close to a few feet tall. Common along wetlands here, Northern blue flag (Iris versicolor) is our native blue flag iris. You may also find nonnative southern blue flag or possibly some yellow relations occasionally escaped into the wild.

Northern blue flag (Iris versicolor)
Northern blue flag (Iris versicolor)

Not-so Edible Uses of Blue Flag Iris

Irises are bitter and toxic and their genus is generally on the do not consume list. Iris species contain the glycoside irisin which irritates both skin and mucous membranes including the digestive system, causing nausea and vomiting. This poison is most prevalent in the fresh rhizomes.

Medicinal Uses of Blue Flag Iris

Some herbalists use a carefully prepared tincture out of dried root for skin diseases and digestive issues relating to the liver, among other conditions. There is a long history of using poisons in small doses as medicine. You may like the book The Poison Path (Amazon affiliate link fyi) if this topic interests you.

Alternative Uses of Blue Flag Iris

Like violets, an infusion of the flowers can be used as a litmus test.

The leaves can be used for weaving.

Northern blue flag (Iris versicolor)
Northern blue flag (Iris versicolor)

Growing Iris Versicolor

When blue flag iris is in bloom many pollinators will visit it including hummingbirds. Photographers take note: it’s a photogenic flower and most visitors linger drinking the nectar making for nice clear pollination pictures. Like other plants in this series, mammals generally leave the irises alone due to their toxicity.

Various caterpillars host on blue flag, including one of my favourite daytime moths, the electric blue, orange-headed Virginia ctenucha (Ctenucha virginica). (Tip: plant some goldenrod for the adults!)

If you have a wet meadow or any wetlands on your property, or have built a pond or rain garden, irises are an all-star plant to landscape with. Blue flag establishes very well and will spread by rhizome, perhaps throughout entire small ponds. So if you’re putting it in a pond you’ve dug and you’re particular about where you want it, you may want to use a pot to segregate it.

Next month’s diary is on red columbine, another one hummingbirds will love. Subscribe to be notified of new plant posts!

And the Usual Cautions:

1) Most medicinal herbs, if edible, are meant to be eaten in moderation, even sparingly. Some require extra preparation. Tannins are toxic if consumed in excess.

2) People can be allergic or sensitive to nearly any plant; try new herbs one at a time at your own risk. For instance, saponins commonly cause stomach upset.

3) For medicinal use, I must recommend receiving a diagnosis and working with a reputed health care provider. I generally do not post specific treatments and dosages because I think that is best between you and your health care provider, and ideally monitored.

4) Anyone pregnant, nursing, or taking prescription drugs should talk to a health care professional before adding new food items to their diet.

5) Many plants have look-a-likes, and sometimes they are poisonous.

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Edible and Medicinal Plants of Canada

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