This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Perennial densely matted herbs, with copiously leafy stems and sterile branches, naked or sparingly leafy flower-stalks and opposite (except sometimes on the flower-stalks) often 4-ranked imbricated broad keeled ciliate leaves each with an almost apical pore, the flowers solitary, erect. Calyx-lobes 5, strongly ciliate. Corolla mostly blue or purple, sometimes white, regular, the petals much longer than the calyx, narrowed into claw-like bases. Stamens 10; filaments subulate to triangular. Ovary less than one-half inferior, the carpels united to above the middle. Follicles erect, except the more or less spreading tips. [Greek, opposite leaved.]
About 4 species, natives of northern regions. Type species: Saxifraga oppositifolia L
Saxifraga oppositifolia L. Sp. Pl. 402. 1753.
Antiphylla oppositifolia Fourr. Ann. Soc. Linn. Lyons II. 16: 386. 1868.
Tufted, stems prostrate, densely leafy, 2'-10' long. Leaves sessile, ovate, obovate or nearly orbicular, purplish, persistent, keeled, fleshy, opposite, or imbricated in 4 rows on the sterile shoots, obtuse, punctate with 1-3 pores, 1"-2 1/2" long, the margins ciliate; flowers solitary, peduncled or nearly sessile, 4"-6" broad; calyx-lobes obtuse, much shorter than the obovate purple petals; calyx free from the ovary and capsule; follicles abruptly short-pointed; seeds rugose.
On wet rocks, Mt. Mansfield and Willoughby Mountain, Vt.; Anticosti, Newfoundland and throughout arctic America to Alaska, south in the Rocky Mountains to Wyoming and to Oregon. Also in Europe and Asia. Summer.