Not to be confused with: Mountsorrel (a village on the River Soar in Leicestershire) where, according to Wikipaedia today, it is presently at a temperature of 9°C, the wind is from the South at 21mph and the humidity is 79%: where 'now' is 15:10 am, Mon 13th Jan 2020.
Easily mis-identified as :
Monk's Rhubarb (Rumex alpinus), which can grow in similar places but is more likely found near houses and roads (and probably Abbeys) on account of it once being popular as a pot-herb, but it is much taller and the leaves, although similarly heart-shaped, are slightly concave rather than slightly convex.
No very close relationship to : Wood-Sorrel (Oxalis acetosella), Pink-Sorrel (Oxalis articulata), Pale Pink-Sorrel (Oxalis latifolia), Spreading Yellow-Sorrel (Oxalis corniculata),
Least Yellow-Sorrel (Oxalis exilis),
Upright Yellow-Sorrel (Oxalis stricta), Pale Pink-Sorrel (Oxalis latifolia),
Purple Pink-Sorrel (Oxalis debilis) nor to Lilac Sorrel (Oxalis incarnata), [plants with similar names belonging to a differing Genus, Oxalis, which belongs to a differing family, Oxalidaceae, although both genera possess salts of Oxalic Acid such as Calcium Oxalate].
Mountain Sorrel is the only member of the Oxyria genus (at least in the UK) but is related to the Rumex genus of
Sorrels. It is native and grows only on mountain grasslands or rocky ledges in wettish places, and has its main presence in Scotland with a few islands of presence in Cumbria and Snowdonia. It is strangely rare in Ireland even though that has plenty of damp rocky mountains, and an introduction to the Isle of Man.
Like other Docks and Sorrels such as Common Sorrel, Mountain Sorrel has an acid taste due to the presence of poisonous Oxalic Acid, specifically the calcium salt, Calcium Oxalate, which forms extremely tiny needle-shaped and extremely sharp crystals called
raphides, which cause mechanical damage to cells when consumed. That said, like other Sorrels, the leaves are still used in salads (not many leaves are used in salads). It is only fatal when great quantities are consumed. It is also rich in Vitamin C, containing 360ppm by weight and used by the Inuit to cure scurvy. The genus name Oxyria, is Greek and means 'sour'. The aerial parts of the plant are all edible when cooked.