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Pontefract Castle
Medieval herb garden blog 48: Green alkanet
Monday, December 01, 2025Week 48 volunteer update
Another wet and dismal day! Carole carried out the weekly flower count. There are 20 species still in flower.
The purple comfrey (Symphytum oficinale) has been overcome by the frost once again. However, the white comfrey is still alive and well.
The purple comfrey after giving in to the frost
It would appear that the white comfrey is a Symphytum longisetum. This is a variety native to Southern Turkey. It is an evergreen species. Unless something strange is happening in the Medieval Herb Garden!
The white comfrey still doing well in the Medieval Herb Garden
Plant of the week: Green alkanet (Pentaglottis sempervirens)
The genus name 'Pentaglottis' is Greek. It means 'five tongues', as the flowers have five sepals (these form the outer parts of a flower). 'Sempervirens' is Latin for 'always alive' or 'evergreen'.
The word 'alkanet' derives from Middle English. This comes from the Old Spanish 'alcaneta', from of 'al-henna'. It indicates a similarity to henna dye.
Its other names are evergreen bugloss and dyer’s bugloss.
Green alkanet is native to southwestern Europe. It is a hardy, bushy, clump-forming, evergreen perennial.
It prefers to be in full sun or partial shade. It grows in moist or well-drained soil of any type. It will grow to a height and spread of 2 to 3ft.
The leaves form a rosette of bristly, coarse, pointed, oval leaves. These grow up to 16 in long. The lower leaves have leaf stalks. Sometimes the leaves have small white speckles.
The hairs on both the leaves and stem can cause skin irritation.
Green alkanet in flower in the Medieval Herb Garden
Green alkanet flowers throughout the year, but mainly during late Spring to early Summer. It has pink flower buds. These open to brilliant blue flowers, similar to forget-me-nots. The flowers are approximately 0.4 inches wide.
There are five sepals. The stamens are hidden inside narrow flower-tubes. These end in a 'white eye' in the centre of the blue flower.
Green alkanet readily self-seeds. It has a deep, fleshy tap root. This makes the plant difficult to totally remove, as any remaining root will produce a new plant.
Culinary uses of green alkanet
Green alkanet has been used in food and drink in the past. The young leaves and shoots of the plant have been eaten as a salad. Historically, the roots were roasted and ground to make a coffee substitute.
Please note that green alkanet is toxic if you consume lots of it. The roots are not edible. They contain pyrrolizidine alkaloids. These are toxic to the liver, even when cooked.
Green alkanet as a dye plant
The roots of green alkanet contain a red dye. This can be used to colour fabrics, yarns and other materials.
The dye is extracted by boiling the roots for a period of time and then straining the liquid. The result can be pale pink to dark red. The colour depends on the mordant used and the length of time the fabric is left in the dye bath.
Folklore and other facts about green alkanet
Green alkanet was first introduced into English gardens in 1700. It was first recorded in the wild in 1724, showing its ability to self-seed.
The roots of the plant were believed to have the power to detect and neutralize poison. In medieval Europe, the root of the plant was often carried by travellers and traders. They hoped it would protect them from poisoned food and drink.
Its nectar-rich flowers are attractive to pollinators. These include bees, hoverflies and butterflies. Its leaves are food for the larvae of the scarlet tiger moth (Callimorpha dominula).
Medieval medicinal uses of green alkanet*
Green alkanet leaves were used as a remedy for burns and ulcers. They would be crushed and combined with vinegar and rose water.
The roots were used to treat skin conditions, respiratory problems, and digestive issues.
Green alkanet was also believed to be astringent (tightening tissues and skin) and a diuretic (helping to pass urine).
*As always, this isn't to be considered medical advice today. Please don't use any plants mentioned in these blogs as medicine without advice from a doctor.
Medieval herb garden blogs
Browse all blogs by our dedicated team of volunteer gardeners at Pontefract Castle. Discover each 'Plant of the Week' as chosen throughout 2025.