Ah, arnica. Renowned for its power to soothe sore muscles, sprains and bruises, and a common gateway drug into the wonderful world of the do-it-yourself apothecary.

Most often it is in the form of arnica oil, where the bright yellow flower heads are wilted and then used to infuse oil that can be used in massage or further processed into a salve or cream.

One place it doesn’t get used though, is in food.

While dandelion petals make for a wonderfully cheery muffin, or can be strewn over the top of a cake to make it divine, arnica embodies that exciting plant power in which a compound that is extremely healing in one form can be fatal in another.

I was surprised to learn when I opened up my Flora of the Yukon (the Yukoner’s plant bible) that there are 11 species in this genus recorded in our territory.

I am familiar with two varieties from my yearly collecting activities, both subspecies of Arnica angustifolia. A third, heart-shaped arnica (Arnica cordifolia), will be familiar to devotees of Bev Gray’s The Boreal Herbal. She tells us that the name comes from the greek arnakis (sheepskin) in reference to the soft, fuzzy leaves. Those leaves were the source of constant worry the first season I discovered arnica’s toxic impact on our inside parts – I was terrified I would mistakenly harvest arnica leaves instead of arrow-leaved coltsfoot for tea early in the season before the blooms appeared.

I haven’t poisoned anyone yet, and I learned a good lesson in getting to know plants across the whole season, not just when the most obvious identifying parts are visible. I wonder if there is any link between the sheepskin reference and one of arnica’s alternate names, wolf’s bane.

The very thing that makes arnica healing is, of course, also what renders it toxic. After all, any compound that alters us physiologically has the potential to be dangerous in too large a quantity.

This is why when learning both edible and medicinal plants it is important to pay attention to the parts of plant used, methods of preparation and administration. For example, some compounds are rendered inert through drying and some are soluble in only oil or in alcohol. Another consideration is that some interact with our own systems only via certain types of contact, such as through the skin, airways, or digestive tract.

The active component of arnica, called helenalin, has different effects on the body depending on how it are administered: it is wonderfully soothing when absorbed through the skin into tired or sore muscle tissue, and nastily irritating if brought into contact with the digestive tract.

I imagine most people don’t have many problems with this kind of multiple personality when buying preparations: this is labelled a tea, so I will drink it; this is labelled a foot rub, so I will not. When you get into harvesting and preparing your own concoctions it becomes more important to understand what you are actually working with in a healing plant, how it can be extracted from the plant, and how it should be used with the body.

As always, I encourage you to Forage On! for both food and medicine.


Arnica

Deadliness: 2/5 You’d have to ingest a lot of flowers to kill you, but keep in mind that preparations are more concentrated.

Poison: Helenalin (sesquiterpene lactone).

Symptoms: upset/blistering of digestive tract, dizziness, tremors, cardiac arrhythmia.

Treatment: Induce vomiting and get medical help immediately.