Cornus subg. Thelycrania
Ill. Handb. Laubholzk. 2: 437. 1909.
Shrubs or trees; rhizomes present or absent. Branches and leaves usually opposite, rarely whorled, subopposite, or alternate at some nodes. Inflorescences cymes; bracts numerous, minute, not petaloid, subtending primary and secondary inflorescence branches, proximal portion adnate to branch, free portion caducous. Pedicels present. Drupes distinct; stone apex rounded, pointed, or with slight dimple.
North America, Mexico, Central America, n, w South America, Eurasia.
Species ca. 30 (11 in the flora).
What is treated here as subg. Thelycrania has almost invariably been called subg. Kraniopsis Rafinesque. That name is invalid, however, because C. S. Rafinesque (1838) apparently treated his new taxon as a genus, not a subgenus, and no publication validating the name at the subgeneric rank has been located.
|1||Leaf secondary veins usually (4–)5–9 per side.||> 2|
|2||Bark splitting longitudinally, appearing braided; lenticels not protruding on 2d year branches; leaf blade abaxial surfaces without tufts of erect hairs in axils of secondary veins.||> 3|
|3||Leaf blade bases cuneate, abaxial surface hairs all appressed and rigid, secondary veins evenly spaced.||Cornus obliqua|
|3||Leaf blade bases rounded or truncate, abaxial surface hairs both appressed and rigid, and erect and curling, most secondary veins arising from proximal 1/2 of blade.||Cornus amomum|
|2||Bark loosely verrucose; lenticels protruding on 2d year branches; leaf blade abaxial surfaces with tufts of erect hairs in axils of secondary veins.||> 4|
|4||Area surrounding lenticels suffused with purple on older branches; leaf blades suborbiculate or broadly ovate, secondary veins 7–9 per side, evenly spaced, tertiary veins usually prominent.||Cornus rugosa|
|4||Area surrounding lenticels not suffused with purple on older branches; leaf blades lanceolate, elliptic, or ovate, secondary veins 5–7 per side, most arising from proximal 1/2, tertiary veins not prominent.||> 5|
|5||Leaf blade abaxial surface hairs appressed except in and near axils of secondary veins.||Cornus sericea|
|5||Leaf blade abaxial surface hairs (except those on veins) all erect.||Cornus occidentalis|
|1||Leaf secondary veins usually 3–4(–5) per side.||> 6|
|6||Leaf blade abaxial surface hairs curved upward, erect, or both erect and appressed.||> 7|
|7||Drupes purple-black; rhizomes absent; stems clustered.||Cornus sanguinea|
|7||Drupes blue to whitish blue or white; rhizomes present; stems solitary.||> 8|
|8||Petioles 2–7 mm; leaf secondary veins evenly spaced; drupes blue to whitish blue.||Cornus asperifolia|
|8||Petioles 8–25 mm; most leaf secondary veins arising from proximal 1/2 of blade; drupes white.||Cornus drummondii|
|6||Leaf blade abaxial surface hairs appressed.||> 9|
|9||Rhizomes present; stems solitary; lenticels protruding and extruding tissue on 2d year branches; bark appearing verrucose; drupes usually white, occasionally pale blue.||Cornus racemosa|
|9||Rhizomes absent; stems clustered; lenticels not or seldom protruding or extruding tissue on 2d year branches; bark appearing braided; drupes blue, pale blue, violet plumbeous, or blue violet, often turning whitish blue to white.||> 10|
|10||Basal secondary leaf vein arising 1–2 mm from blade base; e, c United States.||Cornus foemina|
|10||Basal secondary leaf vein arising 5–10 mm from blade base; California, Oregon.||Cornus glabrata|