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..
Low evergreen shrubs, with small narrow nearly sessile exstipulate leaves jointed to short pulvini, channeled on the lower side by the revolute margins, and small dioecious or rerely polygamous flowers, axillary or in terminal heads. Calyx of 3 sepals. Corolla or 2 or 3 petals, or none. Staminate flowers with 2-4 (mostly 3) stamens, the filaments filiform, the anthers 2-celled, longitudinally dehiscent, sometimes with a rudimentary pistil. Pistillate flowers with a 2-several-celled sessile ovary, the single style cleft into as many stigma-bearing segments as there are ovary-cavities; ovules 1 in each cavity, amphitropous. Fruit a berry-like drupe, containing 2-several I-seeded nutlets. Embryo straight, terete, in copious endosperm.
Three known genera, the following, and the monotypic Ceratiola of the southeastern United States.
Flowers axillary; petals 3.
Flowers in terminal heads; petals none.
1. ╚MPETRUM [Tourn.] L. Sp. Pl. 1022. 1753.
Depressed or spreading herbaceous shrubs, freely branching, dioecious or monoecious, the branches usually densely leafy, the leaves linear-oblong. Flowers inconspicuous, solitary in the upper axils. Sepals and petals mostly 3. Staminate flowers with 3 stamens, the anthers introrse. Pistillate flowers with a globose 6-9-celled ovary, and a short thick style with 6-9-toothed segments. Drupe black to red, containing 6-9 nutlets. [Greek, on rocks, referring to the growth of these plants in rocky places.]
Two known species, the following typical one, and C. rubrum of southern South America.
Empetrum nigrum L. Sp. Pl. 1022. 1753.
Glabrous, or the young shoots and leaves pubescent, usually much branched, the branches diffusely spreading, 2'-10' long. Leaves crowded, dark green, linear-oblong, thick, obtuse, 2"-3 1/2" long, about 1/2' wide, the strongly revolute margins roughish; flowers very small, purplish; stamens exserted; drupe black, purple or red, 2" - 3" in diameter.
In rocky places, Greenland to Alaska, south to the coast of Maine, the higher mountains of New England and northern New York, Michigan and California. Also in Europe and Asia. Crake-berry. Black-berried heath. Wire-ling. Crow-pea. Monox-heather. Heath. Hog-cranberry. Crowberry. Curlew-berry. Grows in dense beds; the fruit much eaten by arctic birds. .Summer.