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..
Erect branching evergreen resinous shrubs, with scaly buds, the foliage fragrant when crushed. Leaves alternate, thick, short-petioled, oblong or linear, revolute-margined. Flowers white, numerous in terminal umbels or corymbs. Pedicels bracted at the base, the bracts scarious, deciduous. Calyx small or minute, 5-toothed, persistent. Petals 5, obovate or oval, obtuse, spreading, imbricated. Stamens 5 or 10 (rarely 5 to 7), exserted; filaments filiform; anthers small, attached by their backs to the filaments, globose-didymous, awnless, the sacs opening by terminal pores. Disk annular, 8-10-lobed. Ovary ovoid, scaly, 5-celled; ovules numerous; style filiform; stigma 5-lobed. Capsule oblong, 5-celled. septicidally 5-valved from the base. Seeds elongated. [Greek, ledon, the plant now called Cistus Ledon.]
About 5 species, natives of the north temperate and sub-arctic zones. Besides the following, 2 others occur on the Pacific Coast. Types species: Ledum palustre L.
Leaves linear, 1"-3" wide; stamens about 10.
Leaves oblong, 3"-8" wide; stamens 5-7.
L. palustre decumbens Ait. Hort. Kew. 2: 65. 1789. L. decumbens Lodd.; Steud. Nomencl. Ed. 2, 20. 1841.
A shrub, about 1° high, the twigs rusty-tomentose. Leaves linear, obtuse, dark green and somewhat rugose above, densely tomentose with brown wool beneath, strongly revolute-margined, 1/3'-3/4' long, 1"-2" wide; flowers 3"s" broad; pedicels very pubescent, 4"-8" long in fruit; stamens 10; capsule obovoid or oval, scurfy, about 2" high and 1 1/2" in diameter, nodding; calyx-teeth less than 1/2" long, broadly ovate to half-orbicular, obtuse.
Ledum groenlandicum Oeder, Fl. Dan. pl. 567. 1771.
Ledum latifolium Ait. Hort. Kew. 2: 65. 1789.
A shrub, 1°-4° high, similar to the preceding species, the twigs densely tomentose. Leaves oblong, obtuse, 1'-2' long, 3"-8" wide, green and slightly rugose above, densely brown-tomentose beneath, strongly revolute-margined; flowers 4"-5" broad, umbellate or short-corymbose; pedicels brown-canescent or tomentose, io"-I2" long and recurved in fruit; stamens 5-7; capsule oblong, canescent, nodding, 3" - 3 1/2" long, 1"-1 1/2" in diameter.