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..
Densely tufted glabrous low evergreen shrubs, with thick rather fleshy imbricated narrow leaves, and solitary terminal erect peduncled white or pink flowers. Calyx 2-4-bracted at the base, the sepals oval, obtuse, somewhat rigid. Corolla campanulate, tardily deciduous, 5-lobed, the lobes obtuse. Stamens 5, inserted at the sinuses of the corolla; filaments short and broad; anther-cells pointed, divergent, obliquely 2-valved; staminodia none. Style slender; ovules numerous in the cells, anatropous. Seeds oblong-cubic, the testa close, reticulated. [Greek, by fives, alluding to the stamens and corolla-lobes.]
Two species, the following typical one of wide distribution in the colder parts of the northern hemisphere, the other Himalayan.
Diapensia lapponica L. Sp. Pl. 141. 1753.
Glabrous, forming dense cushion-like tufts; stems simple or branched, erect or ascending, 1'-3' high. Leaves crowded below, thick, spatulate, sessile, obtuse or acutish, often curved, entire, 3"-6" long, about 1" wide, the margins usually revolute; peduncles rather stout, becoming 1'-2' long in fruit; sepals and' bracts oval; corolla usually white, 3"-4" long, its tube about the length of the sepals and of its oval or oblong obtuse lobes; capsule ovoid, 2"-3" high.