- Name also: Rough Comfrey, Prickly Comphrey
- Family: Borage Family – Boraginaceae
- Growing form: Perennial herb. Fleshy root.
- Height: 60–200 cm (2–6.5 ft.). Stem roughly haired, especially at the top.
- Flower: Corolla bell-shaped (funnel-shaped), evenly expanding, 11–17 mm (0.4–0.65 in.) long, first pink, later sky blue, fused, 5-lobed. Lobes with rounded tips. Corolla mouth with 5 large, tongue-like scales. Calyx fused, 5-lobed, 2–5 mm (0.08–0.2 in.) long, clearly shorter than corolla funnel. Calyx lobes narrowly elliptic with rounded tips. Stamens 5. Gynoecium fused, single-styled. Cymes in axils, single-branched or scorpioid.
- Leaves: Alternate, narrow-stalked, shortly decurrent or usually not decurrent. Blade elliptic with a usually round or cordate base and entire margin.
- Fruit: 4-parted schizocarp. Mericarps oblique, ridged, granular, matt.
- Habitat: Inhabited areas, parks, gardens, banks, coastline. Cultivated and feral.
- Flowering time: June–August.
Species of comfrey have been cultivated for a long time in Finland, initially only as a medicinal but later also as feed and as an ornamental. Prickly comfrey originated in the Caucuses and was first brought to Europe as feed for pigs, rabbits and goats a couple of hundred years ago. No information remains about its use as feed in Finland – the species evidently came here purely as an ornamental plant. This perennial has many attributes compared to its well-known relation common comfrey (S. officinalis), which has a reputation as a medicinal herb: it doesn’t spread as vociferously or take over the whole garden, and it doesn’t emit chemicals which repel other plants. Although the species spreads at a moderate pace and doesn’t seem capable of producing seeds in our climate, it has escaped into the wild in some places. Prickly comfrey’s most common habitat is old gardens and parks, or where it has escaped to nearby roadsides, ditches and banks.
Due to its apparently coherent origin as a cultivated herb, prickly comfrey in Finland mutates very little. Compared to its more common relation common comfrey, the decurrent leaves on the stem are shorter, its flowers are often bluer, and it has an evenly expanding corolla and a short calyx. The species cross easily however and backcrossing also occurs. The hybrid Russian comfrey (S. x uplandicum) shares markers with both of its parent plants, and it is often very diversiform and sometimes extremely difficult to interpret.
In Finland tuberous comfrey is a rare escape. NOT TRANSLATED YET. Selkein erottava tekijä muista raunioyrteistä on sen pienempi koko (yleensä alle 0,5 m), tyveen asti liuskoittuneet verholehdet ja tietysti haaleankeltaiset kukat. Toki muillakin raunioyrteillämme (etenkin rohto) saattaa olla keltakukkaisia muunnoksia.