Neotropical Cornaceae

Description

Trees or shrubs. Leaves opposite or alternate, simple, margins entire or denticulate, primary venation pinnate, arching, trichomes T-shaped, branched or simple when present; stipules very rarely present. Inflorescences terminal occasionally axillary, cymose, involucres petal -like. Flowers bisexual (rarely unisexual and dioecious), small, actinomorphic; sepals 4(-10), connate, adnate to ovary; petals 4(-10), free, valvate; stamens alternipetalous and equal in number to petals, free, anthers dorsifixed, dehiscing via full-length longitudinal slits; ovary inferior, carpels 2, syncarpous. Fruit a grooved, globose or ovoid drupe. Seeds 2, flat.

Notes on delimitation

• Cornus L. is placed in the Cornaceae which typifies the Cornales currently placed in the Asterid clade. (APG III, 2009).

Distribution in the Neotropics

• Found predominately at high elevations (1,400-3,000m above sea level) below the forest canopy in mountainous regions of Central America, Bolivia, Colombia, Ecuador, Mexico and Peru.
• Also cultivated in Brazil as an ornamental and for its wood throughout most of the Neotropical countries.

Distinguishing characters (always present)

• Actinodromous venation.
• Involucres of petal -like bracts subtend the inflorescences.
• Sepals adnate to ovary.
• Petals valvate.
• Ovary inferior.
• Epigynous disk on top of ovary.
• Drupaceous fruit.

Other important characters

• A handy diagnostic trick in the field is to remove a suspected leaf, fold the leaf blade in half horizontally to form a crease, do this repeatedly until you are able to gently tear the leaf along the crease and gently pull it apart. The bottom half of the leaf will appear to hang in mid air, but on closer inspection you can see sticky threads stemming from the leaf veins.

Key differences from similar families

• Some Viburnum species look similar to Cornaceae, but the latter often have 4-merous flowers, they lack stellate indumentum, and their lateral veins ascend towards the apex of the blade (Stevens, 2008 onwards).

Number of genera

• Cornus L.: Cornus disciflora DC., C. excelsa Kunth, C. florida L. and C. peruviana J. F. Macbr.  growing in the Neotropics.
• Nyssa L.: with two species (N. sylvatica Marshall and N. talamancana Hammel & N.Zamora) in Mexico to Panama.

Notable genera and distinguishing features

• See distribution.

Status

• Native.
   

Important literature

APG III. 2009. An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants. Botanical Journal of the Linnean Society. Vol 161: 3. Pp. 105-121.

Kubitzki, K. 2004. Cornaceae.  In: Kubitzki, K. (ed.), The Families and Genera of Vascular Plants, vol. VI, pp. 82-90. Springer Verlag, Berlin.

Lentz, D. L. 2004. Cornaceae. In: Smith, N., Mori, S. A., Henderson, A., Stevenson, D. W. and Heald, S. V. (eds). Flowering Plants of the Neotropics. Pp. 117-8. The New York Botanical Garden, Princeton University Press, Princeton.

Smith, N. 2004. Nyssaceae: In: Smith, N., Mori, S. A., Henderson, A., Stevenson, D. W. and Heald, S. V. (eds). Flowering Plants of the Neotropics. Pp. 273-274. The New York Botanical Garden, Princeton University Press, Princeton.

Stevens, P. F. 2008. Angiosperm Phylogeny Website. Version 9 onwards. http://www.mobot.org/MOBOT/research/APweb/.

Watson, L. and Dallwitz, M.J. (1992 onwards). The Families of Flowering Plants: Descriptions, Illustrations, Identification, and Information Retrieval. Version 3rd March 2009. www.delta-intkey.com.

How to cite

Every, J.L.R. (2010). Neotropical Cornaceae. In: Milliken, W., Klitgård, B. & Baracat, A. (2009 onwards), Neotropikey - Interactive key and information resources for flowering plants of the Neotropics. http://www.kew.org/science/tropamerica/neotropikey/families/Cornaceae.htm.