27. Oxyria Hill, Veg. Syst. 10: 24, plate 24, fig. 2. 1765.
Mountain-sorrel, oxyrie [Greek oxys, sour, and -aria, possession, alluding to acidic leaves]
Craig C. Freeman, John G. Packer
Herbs, perennial; roots fibrous; rhizomes present or not. Stems erect, glabrous. Leaves deciduous, basal, rarely also cauline, alternate, petiolate; ocrea sometimes deciduous, chartaceous; blade reniform to orbiculate-cordate, margins entire to obscurely wavy. Inflorescences terminal, paniclelike or racemelike, pedunculate. Pedicels present. Flowers bisexual, (1-)3-7 per ocreate fascicle, base stipelike; perianth nonaccrescent, greenish to reddish brown, campanulate, glabrous; tepals 4, in 2 whorls of 2, distinct, sepaloid, dimorphic, outer 2 narrower than inner 2; stamens (2-)6; filaments distinct, free, glabrous; anthers white to red or deep purple, elliptic to ovate; styles 2, spreading, distinct; stigmas penicillate. Achenes exserted, yellowish to tan, winged, lenticular, glabrous. Seeds: embryo straight or curved. x = 7.
Species ca. 4 (1 in the flora): arctic and alpine, n, w North America, Europe, e Asia.
Chrtek, J. and M. Šourková. 1992. Variation in Oxyria digyna. Preslia 64: 207-210. Mooney, H. A. and W. D. Billings. 1961. Comparative physiological ecology of arctic and alpine populations of Oxyria digyna. Ecol. Monogr. 31: 1-29.