Mountain sorrel (Oxyria digyna) is an important circumpolar and circumboreal plant. Caribou, geese and musk oxen eat its leaves while lemmings, voles and Arctic hares prefer the roots for nourishment. The leaves, high in Vitamin C, were used by the Inuit and other indigenous peoples to prevent scurvy and, when eaten after a meal, to aid digestion. Even today mountain sorrel leaves can be eaten along the trail to quench thirst when fresh water is not available or can be nibbled as a sour treat. The semi-succulent leaves can also be used as a salad green. The sour taste of the leaves is due to purple anthocyanins.
A native perennial, mountain sorrel grows in Arctic, alpine and subalpine habitats from 4,000 to 13,000 feet. It can be found from Alaska to Greenland south in the higher mountains of North America as well as in Asia and Europe. Its ecology is rock crevices and scree slopes where moisture from snowmelt is abundant and where the plants have protection from drying winds.
A member of the Buckwheat Family (Polygonaceae), mountain sorrel, is also commonly called alpine sorrel. A few to several erect, unbranched stems arise from a tough, woody taproot. The simple, entire leaves have long stalks (petioles) and are broadly heart or kidney-shaped and are mostly basal. The flowering stems and petioles are somewhat reddish. As the leaves lose chlorophyll in the fall the leaves turn reddish.
Mountain sorrel flowers are densely clustered along the upper half of the erect stems and mature from the bottom up (panicle). The small flowers have four sepals and no petals. The flowers begin greenish and turn red with age. There are usually six stamens and a superior, one-celled ovary.
Each flower can develop into a one-seeded, winged achene that does not split open when dry. Reproduction is by seeds, but mountain sorrel can also spread by rhizomes.
There are morphological and physiological differences between Arctic and alpine populations:
1) Arctic mountain sorrels have inflorescences with more branches, wider leaf blades and flowers with a more stable number of stamens.
2) Arctic plants have more tendency to reproduce asexually by rhizomes and have lower seed production than alpine populations.
The genus name, Oxyria, comes from the Greek “oxys” meaning sharp or sour and “aria” meaning possession and refers to the sour taste. The Greek work “digyna” means two women and refers to the two carpels, giving mountain sorrel its species designation.
These mountain sorrel specimens were photographed in August at and near the top of Mount Lassen in Lassen Volcanic National Park CA.