The Cornaceae

"Dogwood Family"


Cornus drummondii	Cornus alternifolia
Roughleaf Dogwood	Pagoda Dogwood

The Cornaceae family is comprised of 13 genera made up of approximately 130 different species. Cornus, the major genus of the family is made up of 4-46 species, the Mastixia genus has 13-25 species, the Nyssa genus has 5-10 species, and the Campothotheca, Davidia and Diplopanax all have 1 species. These plants have a widespread distribution, but are most commonly found in the northern temporate regions. In the United States and Canada there are 14 species of Cornus and 3 species of Nyssa

Click here for a distribution map of the Cornaceae in the U.S.A.

Vegetative Characters

trees or shrubs, sometimes suffrutescent subshrubs
leaves simple, entire to obscurely serrate, opposite or sometimes alternate
leaves often with arching secondary veins
usually deciduous and exstipulate
inflourescence determinate, cymose and corymbose, umbellate, capitate, paniculate, or sometimes reduced to a single flower
sometimes subtended by large, usually white petaloid bracts (picture below), terminal or axilary
flowers actinomorphic, perfect or imperfect, epiginous, small
flowers with nectariferous disc at ovary apex
flowers sessile or nearly sessile
calyx of 4-5 sepals, distinct, small and inconspicuous, often reduced to teeth around upper edge of ovary.
corolla of 4-5 petals, distinct, white, purple, or yellow

Reproductive Characters

androecium of 4-5 stamens, sometimes up to 10, biseriate with outer whorle opposite petals.
filiaments distinct, anthers usually dorsifixed or basifixed.
dehiscing longitudinally
gynoecium of 1 pistil, 2-carpellate, sometimes 1-carpellate.
inferior ovary, 2- or sometimes 1-locular, capped by nectariferous disc at apex.
ovules 1 in each locule, placentation axial, style 1
stigmas capitate or lobed
fruit usually a drupe with one furrowed pyrene
endosperm copious, oily, embryo small to large

Diagnostic Characters

trees or shrubs
4- to 5-merous perianth and androecius
very reduced sepals
2-carpellate inferior ovary capped by a nectariferous disc.
solitary, pendulous ovule in each locule.
drupe with a single furrowed stone
iridoid compounds commonly present
tissues with calcium-oxalyate crystals

Economic Importance/Fun Facts

eddible fruits from Cornus mas (Cornelian-cherry) see picture below.
ornamental trees and shrubs.
indians used the aromatic bark and roots of Cornus florida as a remedy for malaria
the dogwood nickname comes from the fact that a long ago custom in England was to wash dogs with a concoction made from dogwood bark. It was supposed to cure mange.
When Christ was on earth, so the legend goes, dogwood trees grew to towering sizes, dwarfing many of the other trees in the Holy Land. It's branches were strong and interwoven, its simple white blossoms large and unmarked. In fact it was the perfect tree for a hanging, and so it was that the dogwood was chosen to make the cross upon which Jesus was crucified. Before his final hour, so the legend goes, Jesus made a promise which still holds good. As an anonymous poet put it long ago, here is that promise: Not ever again shall the dogwood grow To be large enough for such a tree, and so Slender and twisted it shall always be With cross-shaped blossoms for all to see. The petals have bloodstains marked in brown And in the blossom's center, a thorny crown. All who see it will think of me, Nailed to a cross from the dogwood tree. Protected and cherished this tree shall be A reflection to all of my agony.

Evolutionary Adaptations and Relationships

the Cornaceae are a monophyletic group but defined broadly to include Nyssaceae and Alangiaceae (Xiang et al. 1998).
two major clades are recognized in the Cornaceae: nyssoid-mastixioid clade (unisexual, 5-merous flowers) and a cornoid clade (bisexual, 4-merous flowers)

Glossary of Terms

suffrutescent: Slightly or obscurely shrubby.
exstipulate: Having no stipules.
biseriate: Arranged in two rows.
pyrene: The stone of a succulent fruit made up of the endocarp and the seed.
Tepal: A division of the perianth--a sepal or a petal--of a flower in which the calyx and corolla are almost identical in appearances.
-merous: A suffix preceded by an Arabic number or numeric prefix such as tri-, indicating how many of each part a flower possesses; 5-merous would be a flower with 5 sepals, 5 petals, etc., while trimerous would have three of each part.

References and Links

Zomlefer, Wendy B., 1994. Guide to Flowering Plant Families. The University of North Carolina Press Chapel Hill, NC USA.
Judd, W. S., C. S. Campbell, E. A. Kellogg, P. S. Stevens. 1999. Plant Systematics: a phylogenetic approach. Sinauer Associates, Inc. Sunderland, MA U.S.A.
http://www.wisc.edu/botit/img/bot/401/Magnoliophyta/Magnoliopsida/Rosidae/Cornaceae/Cornus/C_stolonifera_EP_.jpg
http://glossary.gardenweb.com/glossary
http://www.csdl.tamu.edu/FLORA/mi01/mi01032.jpg
http://www.biosurvey.ou.edu/shrub/codrw2.jpg
http://web.knoxnews.com/news/hughs/ih04022001.shtml
http://www.hort.uconn.edu/plants/campus/conncol/27/27a.jpg
http://www.mtsn.tn.it/didattica/plantwatch/corniolo.jpg
http://www.noble.org/imagegallery/woodhtml/wood1-66/W261.jpg

Pictures


large white petaloid bracts	Cornus


Cornus florida	Cornus mas

For questions or feedback, contact: Kelly McKay