Cladrastis kentukea
common name: Yellowwood

After his visit to New Harmony in 1818, Rafinesque moved to Kentucky and held a professorship at Transylvania University in Lexington. Just months before Robert Owen purchased New Harmony, Rafinesque introduced the genus to which the yellowwood tree belongs:

C. S. Rafinesque, "On a New Tree of Kentucky Forming a New Genus Cladrastis Fragrans," Cincinnati Literary Gazette 1 (21 Feb. 1824) 60.

Interestingly, of the four known species in Cladrastis, only the yellowwood is native to the United States. Two others occur in western China, and the remaining one, in Japan.

The image shown here from The Morton Arboretum Quarterly, v. 16, no l, Spring 1980, is the work of Nancy Hart-Stieber and the Arboretum. I thank the Arboretum for permission and invite you to visit the Arboretum (link below).

Rafinesque wrote in the article cited above:

I discovered in 1822, a new tree on the banks of the river Kentucky, which I noticed in the Kentucky Gazette under the name of virgilia alba; but having seen it only in seed, and not in bloom, I suggested the possibility of its being a peculiar genus. I have last year observed the blossoms of that tree, and found that although decandrous like the virgilia, they are not papilionaceous, but irregular pentapetalous like the cercis. It must therefore constitute a peculiar genus, which I propose to call cladrastis; meaning brittle branches. It bears no peculiar vulgar name, being known by few individuals; the name of yellow locust might be given to it, if it was not already applied to the virgilia lutea . . .

The tree is remarkable by uniting the characters of several others, it has the stem and wood of the mulberry, the leaves like the ash, and the flowers like the locust or Robinia in color and scent; but in long loose panicles and shaped rather like the cercis or red-bud. It grows on the banks of the rivers, Kentucky, Rockcastle, Cumberland, Laurel, Dick, &c. in the alluvions or bottoms, but is not very common. It is a beautiful ornamental tree, rising from 30 to 60 feet, its blossoms which appear between the 15th and 30th of May, have a delightful scent, stronger than that of the common locust, and more similar to the scent of Orange flowers. Its roots which are yellow, die [dye] a citron color, and the wood which is a yellowish white, dies [dyes] also another yellow shade. This tree is therefore highly valuable and ought to be introduced in our gardens, &c.

Many books and the sort of tree labels you see in parks identify the yellowwood as Cladrastis lutea. However, this name became obsolete with the publication of

Velva E. Rudd, CLADRASTIS KENTUCKEA, Phytologia, 21 (1971) 327.

Rudd points out that the species was previously credited to F. Michaux from an 1813 publication. She writes, "Unless proof can be found that the title-page date of 1811 for Dumont de Courset, Le botaniste cultivateur, ed. 2, vol. 6, is incorrect, the epithet Kentuckea has priority over lutea." The spelling has since been changed to kentukea. (The K is not capitalized.)

In the 2005 Indiana Big Tree Register (Indiana Department of Natural Resources, Division of Forestry), the state's largest yellowwood is listed with a height of 63 feet, circumference of 98 inches, and average crown spread of 33 feet. This tree stands on the Indiana University campus near Rawles Hall along 3rd Street.

The national champion yellowwood (in 1998) stood 72 feet high in Cincinnati, Ohio, with a circumference of 276 inches and average crown spread of 73 feet.

Constantine Samuel Rafinesque, naturalist
Morton Arboretum Home Page
Yellowwood State Forest, near Nashville, Indiana
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