One of my favourite things about plant medicine is its ability to heal without consuming it. Simply being surrounded by plants makes people feel healthier and have a stronger sense of wellbeing.

Wandering in the woods, sitting in a meadow, putting hands in soil, decorating with houseplants - for many people, these activities are grounding, calming, energizing, and healing. It really does feel like magic. There are many scientific studies to support how human health benefits from being outside in nature, or even having a single plant in a room or a view of a tree from a hospital window. We are hardwired to be in nature, and thus we are healthier from it.

From the earliest times, medicinal plants have been crucial to sustaining the health and wellbeing of humankind. Before modern science gave insight into human anatomy and chemistry, medicine workers relied on intuition, and even magic, mysticism, and age-old traditions.

Though it cannot be proven how the medicinal uses of plants were first discovered (trial and error or intuition?), what is interesting is that the same plants across the world were used for similar, if not the same, uses by different cultures who had no way of communicating. It makes sense to me that in that time, people would take clues from a plant itself to determine what medicinal action it may (or may not) provide. When the way a plant looks gives insight into how its medicinal use might be determined, this theory is called the Doctrine of Signatures.

The Doctrine of Signatures is a Western Herbal Medicine theory that comes from Medieval Europe, stating the connection between how a plant looks (its signature) with how it might be used medicinally.

Let's take a look at a few plants which incorporate the Doctrine of Signatures. The first two are based on their colour, well the others look at their design, shape, or texture.

Greater Celandine (Chelidonium majus) is a plant historically used as medicine in Europe and Western Asia. It has yellow flowers and the plant secretes a yellow juice (which can be irritating) and post-consumption, it stains the urine yellow.

As yellow is associated with bile, this plant was considered beneficial for biliary complaints (liver- and gallbladder-associated concerns), including gallbladder infection, gallstones, and liver disease. Perhaps the yellow inner-stem and bitter juices gave clues to its use in promoting gallbladder, liver, and bowel function. Note this plant can be toxic to the liver at certain doses, so the practitioner must be diligent to keep it within the safe therapeutic range.

St. John’s Wort (Hypericum perforatum) is another plant for which the medicinal use was related to its colour. Having yellow flowers, the herb was used in the past to treat jaundice and ‘choleric’ humours.

Lungwort (Pulminaria officinalis) dons mottled leaves that resemble diseased lung tissue. This plant is used medicinally to treat respiratory ailments, which its name reflects.

Skullcap (Scutellaria lateriflora) is a nervous system tonic herb, and one I use frequently. The name Skullcap is due to the appearance of the plant’s flowers. Upon viewing the flowers from above, they resemble a skull. Skullcap is advantageous to treat afflictions of the head and nervous system.

The seedpods of Shepherd’s Purse (Capsella bursa-pastoris) are heart-shaped. From a Doctrine of Signatures viewpoint, this may indicate the plant’s use in healing any case of bleeding. The seedpods are plentifully located along the stem and branches, leading up to the bundle of flowers at the top of the plant. This indicates the plants use is to staunch bleeding.

I like to think that Cleavers (Galium aparine) shows a signature for its use as well. Cleavers cling to your clothing as you walk past it. This action reminds me of the way it clings onto toxins in the lymphatic system of the body and helps carry them away as waste products, as it is an effective lymphatic herb.

Doctrine of Signatures can be noticed among many plants. Though this is far from a scientific approach, and some of it can be regarded as a reach, it is fun and interesting to imagine how plant uses may have been discovered in the past. I encourage you to go outside and take a look around.

Look closely at the plants - their colour, shape, design, texture - and see what clues you could imagine the plant might be useful for. And while you’re doing that, put your hands in soil, take some deep breaths in nature and bask in the healing benefits of being a part of it.

(*always consult a Medical Herbalist or Physician if you have any health conditions or are pregnant)

Lauren Truscott Waddell, RHT, CHHC