Common Name: Comfrey, Knitbone
Scientific Name: Symphytum officinale
Family: Boraginaceae (Borage)
A native plant often grown by organic gardeners – it is a useful addition to the compost heap adding nutrients and speeding up the composting process. A useful plant feed can be made by soaking comfrey leaves and stems in a bucket for 1 week, the resulting liquid is smelly and is used diluted 1:10.
This roughly hairy plant has oval leaves alternating up the round hairy stem. It grows to around 1m in height and is bushy in form. The bell-shaped flowers hang in cymes, opening in order along their stalk. It prefers wet areas and muddy ground beside ponds and rivers.
Comfrey was traditionally a food plant, the leaves were battered and fried to produce fritters. However, be careful you pick the correct species – leaves of Symphytum officinale contain very little of a group of compounds call pyrrolizidine alkaloids (which can cause liver damage if taken in quantity for an extended period) but other comfreys including those grown for gardening purposes (rough comfrey, Russian comfrey) contain far higher levels and are not safe to consume. All three species have similar white/pink/mauve bell-shaped flowers (which bees love!) so look at whether the leaf edge continues as a wide frill down the hairy stalk – this marks out Symphytum officinale from the rest.
This useful plant was formerly known as Knitbone, which echoes its scientific name Symphytum – “to bring together” – and was traditionally used to speed the healing of broken bones, sprained ligaments and wounds. Comfrey contains allantoin, a chemical that speeds up cell regeneration and hence healing. An easy way to use this plant is as a fresh poultice – simply take a fresh leaf, bruise it well and apply to the affected area. This can be held in place by a bandage for up to 24 hours before replacement. The active ingredients can also be extracted into oil and used as a salve.
Loosely fill a Perspex bowl with comfrey leaves. Pour in enough good quality vegetable oil (olive, sunflower, almond) to cover and coat the leaves. Place in a bain-marie, or over a saucepan half-full of boiling water, and allow the bowl to simmer for 2-3 hours. Check occasionally and top up the water level underneath if needed. Once the oil has turned a deep green, turn off the heat. Once cool, strain off the oil (separate and pour off a water layer if present). This comfrey oil can be used as it is, or thickened into a salve by heating over a bain-marie with 8g of beeswax (or shea butter) per 100ml comfrey-infused oil. Pour into clean, sterilised jars and label.