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..
Shrubs, undershrubs or trees, with simple opposite, verticillate or alternate, usually entire leaves, and regular perfect polygamous or dioecious flowers in cymes, heads or rarely solitary. Calyx-tube adnate to the ovary, its limb 4-5-dentate, or none. Petals generally 4 or 5, sometimes wanting, valvate or imbricate, spreading, inserted at the base of the epigynous disc. Stamens as many as the petals or more numerous, inserted with them; filaments subulate or flat. Ovary inferior, 1-2-celled in our species; style 1, short or elongated; ovules 1 in each cavity, pendulous, anatropous. Fruit a drupe, the stone 1-2-celled, 1-2-seeded. Seeds oblong; embryo nearly as long as the endosperm; cotyledons foliaceous.
About 16 genera and 85 species, most abundant in the northern hemisphere. Flowers perfect. 4-parted: ovary 2-celled.
Flowers cymose, not involucrate.
Trees or shrubs.
Undershrubs with creeping rootstocks.
Flowers polygamous or dioecious; petals minute or none; ovary 1-celled.
1. CÓRNUS [Tourn.] L. Sp. Pl. 117. 1753.
Shrubs or trees, with simple mostly entire opposite verticillate or rarely alternate leaves, and small white greenish or purple flowers, in cymes. Calyx-tube top-shaped or campanulate, its limb minutely 4-toothed. Petals 4, valvate. Stamens 4. Ovary 2-celled; stigma truncate or capitate; ovules 1 in each cavity. Drupe ovoid or globular, the stone 2-celled and 2-seeded. [Greek, horn, from the toughness of the wood.]
About 20 species, natives of the north temperate zone, Mexico and Peru. Besides the following, 3 or 4 others occur in western North America. Type species: Cornus Mas L. Leaves opposite.
Leaves broadly ovate or orbicular; fruit blue.
Leaves ovate or ovate-lanceolate.
Fruit blue; stone pointed at the base.
Fruit 1 1/2" in diameter, the stone longer than broad.
Fruit 3" in diameter, the stone broader than long or as broad.
Leaves scabrous above.
Leaves not scabrous.
Leaves glabrate, or minutely appressed-pubescent beneath.
Leaves ovate, short-pointed; twigs purple.
Leaves ovate-lanceolate, acuminate.
Fruit white; twigs grey.
Fruit pale blue; twigs reddish.
Leaves alternate, clustered at the ends of the flowering branches; fruit blue.