Herbarium Specimen

Figure 5

Osage orange, Maclura pomifera, (Raf.) Schneid.

To see labels, point to the image.

photo of Lewis's herbarium specimen

Academy of Natural Sciences, Philadelphia

This is one of the more problematic of the 133 or 134 known botanical specimens collected by Lewis and Clark.1 Most of the sheets in the collection have annotations or labels that give some indication of when and where the specimens were collected. A few of the labels (on thick bluish or reddish paper) are in Lewis's hand, but most of his original remarks were copied by Frederick Pursh onto small pieces of white paper, which contain the earliest information available today. This is one of only three for which neither places nor dates are known, which accounts for Thomas Meehan's memo that there was no label or memorandum with it when he got it from the American Philosophical Society. The folded piece of white paper at lower left is a small envelope or "packet" to hold pieces of the specimen that might have been loose when it was first mounted, or might have fallen off afterwards.

Lewis's letter to Jefferson containing his 500-word description of the tree was dated March 26, 1804. Only twice was the "Osage Apple" mentioned in the journals, both at Camp Dubois before the expedition officially began. Clark wrote in his Remarks for 7 April 1804: "the leaves of Some of the Apple trees have burst their coverts and put fo[r]th." Three days later, with daily temperatures at sunrise still well below freezing, he observed: "no appearance of the buds of the Osage Apple," whereas the plum trees had already "put forth their leaves and flower buds." Pierre Chouteau, a prominent St. Louis businessman and Indian agent to the Osages, told Lewis he had introduced the tree to the vicinity of the town in the late 1790s. Chouteau's own saplings had as yet produced neither flowers nor fruit, which suggests that the specimens Clark saw were about the same age.

The dates of Lewis's and Clark's references to the "Osage apple" notwithstanding, it is doubtful that either of them collected this thorn-studded branch and those few leaves in the spring of 1804. The tree is deciduous, that is, leaves fall from it in the late fall or early winter, and are replaced late in the following spring. This specimen has fully mature leaves that would normally not be seen until late spring or early summer. In fact, the plant flowers in the spring, and it is surprising that no flowers or even buds are present. Again, this suggests the specimen was made in mid to late summer. As noted above, Clark comments that when he observed the tree, buds were not yet present. Lewis specifically mentioned in his letter to Jefferson that he was sending young cuttings ("slips"), which could have been easily harvested in April since the Osage orange sends up shoots from its far-reaching roots. He said nothing about a pressed specimen. Therefore, inasmuch as this specimen has traditionally been regarded as a Lewis and Clark collection, and despite the absence of a label in either explorer's hand, it must continue to be considered as having been collected by one of them, and that could only have been done after the expedition returned to St. Louis in September of 1806.

As cryptic as it may appear, any professional botanist can read the entire chronological history and justification of a plant's classification, or taxonomy, in an abbreviated tracing such as the one that follows the heading on the Lewis and Clark Herbarium label at lower center of the specimen sheet shown here. The currently accepted Latin binomial consists of the name of the genus, Maclura, and the species denominator, or "specific epithet," pomifera. The abbreviation "Raf." in parentheses signifies that the first botanist to identify this specimen was Constantine Samuel Rafinesque (1783-1840). However, "C. K. Schneid., Ill. Handb. Laubholzk. 1:806" relates that Camillo Karl Schneider (1876-1951), a German botanist, garden architect, horticultural journalist, and author of several books on trees, proposed the botanical name by which the Osage orange tree is known today. He published it in his Illustriertes Handbuch der Laubholzkunde, a monumental illustrated manual on woody cultivated plants, which appeared in twelve parts arranged in two volumes between 1904 and 1912. The name Maclura pomifera was entered on page 806 of the first volume, which was published in 1906.

Soon after the expedition's end, Rafinesque saw saplings growing from slips in Bernard McMahon's garden in Philadelphia—which was part of St. Peter's Churchyard—and may have heard details about the fruit from Lewis in person, or from someone to whom Jefferson had conveyed the substance of Lewis's letter. In any case, in December of 1817 he designated it Ioxylon pomiferum ("poison apple"), basing his description on garden plants growing in Philadelphia.2 The following year, Thomas Nuttall (1786-1859) described the species without acknowledging Rafinesque's earlier name (about which Nuttall may not even have known). He proposed Maclura in honor of his friend, geologist William Maclure. Nuttall's specific epithet was aurantiaca, meaning "orange-colored." In 1906, the German dendrologist Camillo Karl Schneider (1876-1951), aware of Rafinesque's name, ioxylon, proposed Maclura pomifera, purposely pairing Nuttall's generic designation with Rafinesque's specific epithet as required by the International Code of Botanical Nomenclature. The pomifera remains the only species in this monospecific genus.

Figure 6

William Maclure (1763-1830)

Portrait by Charles Willson Peale, ca. 1800

Painting of William Maclure

Ewell Sales Steward Library. The Academy of Natural Sciences of Philadelphia

Maclure was president of the Academy of Natural Sciences of Philadelphia (1817-39), a member of the American Philosophical Society, a social activist and the "father of American geology." In 1826 he boarded the keelboat Philan-thropist–the "Boatload of Knowledge"–along with a dozen other writers, educators, scientists and artists, including Robert Owen (1801-1877), Charles-Alexandre Lesueur (1778-1846), and Thomas Say (1787-1834). The party cruised down the Ohio to settle at the utopian village of New Harmony, Indiana. Maclure's principal achievement there was his founding of the Working-men's Institute, which included the first library in Indiana. An Osage orange tree, possibly planted by Maclure, still grows in front of the house he occupied at New Harmony.


1. Many of those species are represented by more than a single herbarium sheet. Of that number, 179 specimens are on permanent loan to the Academy of Natural Sciences by the American Philosophical Society. Nine or perhaps ten more are to be found at the Royal Botanic Gardens at Kew, England. A previously unknown Lewis specimen of a grass gathered in North Dakota in 1806 was discovered at Kew in 2005.

2. When Rafinesque died in 1840, his herbarium was obtained by Elias Durand, who was then at the Academy of Natural Sciences in Philadelphia. Unfortunately, Durand kept only a few of Rafinesque's plant specimens, discarding thousands of them, including many that Rafinesque had used to characterize new species as well as types. In the case of this species, it is not known if Rafinesque actually had a specimen in his herbarium, but it is likely he did.

Funded in part by a grant from the NPS Challenge-Cost Share Program