Symphytum asperum

Lepech.

Prickly Comfrey

Boraginaceae Edible: Leaves Potential hazards — see below 2,156 iNaturalist observations

Has a deadly poisonous lookalike — see comparison below

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Summary

Symphytum asperum is a flowering plant of the genus Symphytum in the family Boraginaceae. Common names include rough comfrey and prickly comfrey. It is the tallest Symphytum species. It is native to Asia, and it is known in Europe and North America as an introduced species and sometimes a weed. Symphytum × uplandicum, the naturally occurring hybrid with the common comfrey (Symphytum officinale), is the economically most important kind of comfrey.

Description

A bush. It grows 1.2-1.5 m high and spreads 1.5-2 m wide. The leaves are oval and have bristles. The leaves are 25 cm long. The flowers are tube shaped and 18 mm long. The start pink but turn blue.

Edible Uses

Young leaves can be eaten raw or cooked, though most people find them unpleasant — they are hairy, mucilaginous, and mineral-rich. Chopping them finely and mixing into salads helps disguise the texture. Young blanched shoots make a reasonable asparagus substitute. Older leaves can be dried and brewed as a tea, and peeled roots can be sliced and added to soups. A tea is also made from a combination of dried leaves and roots. Roasted roots can be blended with dandelion and chicory roots as a coffee substitute.

Medicinal Uses

The leaves are anodyne, mildly astringent, demulcent, emollient, expectorant, haemostatic, refrigerant, and vulnerary. Applied as an external poultice, they help treat cuts, bruises, and sprains. Internally, a leaf tea is used for chest complaints. The plant contains allantoin, a cell-proliferating compound that accelerates healing. Leaves are harvested in summer and can be used fresh or dried.

Known Hazards

No reports of toxicity have been seen for this species, but the following reports have been seen for S. officinale. This plant contains small quantities of a toxic alkaloid which can have a cumulative effect upon the liver. Largest concentrations are found in the roots, leaves contain higher quantities of the alkaloid as they grow older and young leaves contain almost none. Most people would have to consume very large quantities of the plant in order to do any harm, though anyone with liver problems should obviously be more cautious. In general, the health-promoting properties of the plant probably far outweigh any possible disbenefits, especially if only the younger leaves are used.

Distribution

It is a temperate plant. It suits hardiness zones 5-10.

Where It Grows

Asia, Australia, Britain, Caucasus, Europe, Fiji, India, Iran, Middle East, Pacific,

Cultivation

Tolerates most soils and situations but prefers a moist soil and some shade. Grows well in heavy clay soils. Best grown in an open sunny site in a deep rich soil if it is being grown for compost material. Plants can be invasive, often spreading freely by means of self-sown seed. They are also very difficult to remove, the root system is very deep and even small fragments of root left in the soil can produce new plants.

Propagation

Sow seed in spring or autumn in a cold frame. Prick seedlings into individual pots once large enough to handle and grow on in the greenhouse through their first winter. Plant out in late spring or early summer after the last expected frosts. With sufficient seed, an outdoor sowing in situ in spring can be attempted. Division works at almost any time of year — chop off the top 7cm of root just below soil level with a spade. The original root will regrow, and each of the removed root tops can be potted up or planted directly into a permanent position.

Other Uses

The plant grows rapidly and produces large volumes of biomass. It tolerates multiple cuts per year, making it useful as an instant compost source for crops like potatoes — wilted leaves can be layered in planting trenches or applied as mulch in no-dig gardens. Soaking the leaves in a small amount of water for a week yields a liquid feed high in potassium, well suited to tomatoes. The leaves are also a valuable addition to the compost heap. A gum extracted from the roots was historically used to treat wool before spinning.

Notes

There are about 25-35 Symphytum species.

Dangerous Lookalikes

This plant can be confused with the following toxic species. Always verify identification carefully before consuming any wild plant.

DEADLY

Foxglove

Digitalis purpurea

Jörg Hempel

Safe

Prickly Comfrey

Symphytum asperum

Foxglove: Soft velvety hairy leaves, tall spike of tubular purple/pink spotted flowers, leaves feel like soft felt.

Prickly Comfrey: Rough/bristly hairy leaves, purple/blue drooping bell flowers, leaves feel like sandpaper.

Synonyms

Symphytum asperrimum Donn. ex Sims

Also Known As

Rough comfrey, Soft Comfrey

References (7)

Bremness, L., 1994, Herbs. Collins Eyewitness Handbooks. Harper Collins. p 219
Cundall, P., (ed.), 2004, Gardening Australia: flora: the gardener's bible. ABC Books. p 1385
Nova Acta Acad. Sci. Imp. Petrop. Hist. Acad. 14:442. 1805
Plants for a Future database, The Field, Penpol, Lostwithiel, Cornwall, PL22 0NG, UK. http://www.scs.leeds.ac.uk/pfaf/
Smith, A.C., 1991, Flora Vitiensis Nova, Lawaii, Kuai, Hawaii, Volume 5 p 152

Show all 7 references

World Checklist of Useful Plant Species 2020. Royal Botanic Gardens, Kew
Zeven, A. C. & de West, J. M. J., 1982, Dictionary of cultivated plants and their regions of diversity. Wageningen. p 88