A Lucky Find

Seed Packets Shed Light on Philadelphia's Horticultural History

By: Robert McCracken Peck

Originally Published in 2020

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BECAUSE OF the ephemeral nature of gardens and the plants they contain, the history of horticulture is generally studied through the lens of botanical treatises, commercial catalogs, personal diaries, paintings, photographs, and surviving correspondence. Libraries are the places garden historians most often turn to for the information they seek. Archaeological research is less frequently attempted because it is expensive, time-consuming, and more challenging to undertake. Nevertheless, it can be an invaluable means of understanding how gardeners have assisted one another in cultivating “God’s creations” through time.

A drawing of the Woodlands house, with a sky of rolling clouds.
William Russell Birch (1755-1834). “Woodlands, the Seat of Mr. Wm. Hamilton, Pennsylvania,” from Country Seats of the United States, 1808. https://www.woodlandsphila.org/hamiltons-landscape.

The serendipitous discovery of several hundred seed packets, dating from the late 18th to the early 19th century, has demonstrated the applicability of archaeology to this kind of study by providing a rare glimpse at the day-to-day workings of horticulture in North America during one of its most significant and active periods. The seeds were found in the attic of The Woodlands, William Hamilton’s large country estate located on the western edge of William Penn’s city of Philadelphia. Today the mansion and its remaining grounds are within The Woodlands Cemetery, just blocks beyond the University of Pennsylvania campus. Annotations on the paper wrappings containing each set of seeds provide previously undocumented information about the botanical activities of Hamilton (1745–1813), one of North America’s best-connected and most influential horticulturists.

A painted portrait of the Hamiltons.
William Hamilton and Ann Hamilton Lyle portrait, oil painting by Benjamin West (1730–1813). Mrs. Lyle was William Hamilton’s niece. Art and artifact collection [Collection #3137], Historical Society of Pennsylvania. Reproduced with permission from the Historical Society of Pennsylvania.

When William Hamilton turned 21 in 1766, he inherited his grandfather’s estate. He had a deep love of horticulture, which his family’s wealth enabled him to pursue with gusto. He recruited several professional gardeners and, with their assistance, helped to make Philadelphia a major center of botanical activity in the late 18th century. Initially, he shared his botanical knowledge and enthusiasm for exchanging both useful and decorative plants with such notable figures as William Bartram (1739–1823), Benjamin Smith Barton (1766–1815), and André Michaux (1746–1802). Later he helped Thomas Jefferson (1743–1826) and the American Philosophical Society propagate the plants that were collected as seeds and cuttings by Meriwether Lewis (1774–1809) and William Clark (1770–1838) during their pioneering cross-country expedition of 1803–1806. Today, thanks to the packets found in The Woodlands’ attic, we know more about the full extent of Hamilton’s horticultural network than we had ever been able to determine through the written record alone.

The historic seed packets were discovered in 1992 by Timothy Preston Long, a registered architect with the National Park Service. He was conducting a structural survey of The Woodlands Mansion at the time. “I came upon them quite unexpectedly,” recalls Long, “under piles of dust, lying between two levels of joists on the back side of the plaster and lath ceiling of an unfinished section of the building’s attic.” The packets were scattered and not always intact. They presumably fell out of stored possessions of Hamilton’s after his death.

Drawing of the Woodlands house from a bridge across a river.
The Woodlands from the Bridge at Grays Ferry. Drawn by James Peller Malcolm, 1792. The Dietrich American Foundation. Courtesy of The Woodlands Trust for Historical Preservation.

The Woodlands

A Philadelphia Estate “In The English Manner”

When Hamilton inherited The Woodlands it was already an estate of over 300 acres on the Schuylkill River, above Grays Ferry. He would double its size during his lifetime. The land was acquired in 1735 by his grandfather Andrew Hamilton (1676–1741), William Penn’s famed lawyer. Andrew willed the property to his youngest son, also named Andrew (1713–1747), the father of William. Soon after taking control of the property, William built a Georgian-style mansion with a grand, two-storied portico overlooking the Schuylkill and began to develop the gardens. After the American Revolution, the German botanist and surgeon Johann David Schöpf noted the remarkable appearance of The Woodlands in a book he wrote on his American travels from 1783 to 1784. “The taste for gardening is, at Philadelphia as well as throughout America, still in its infancy,” he observed. “There are not yet to be found many orderly and interesting gardens. Mr. Hamilton’s near the city is the only one deserving special mention.”

Hamilton achieved his reputation as one of America’s leading horticulturists by applying his inherited wealth to his own serious study of botany and landscape architecture over the 46 years that he lived at The Woodlands. During an extensive tour of England from 1784 to 1785, he visited gardens designed by Lancelot “Capability” Brown, William Shenstone, and other proponents of the “English style.” When he returned to Philadelphia, Hamilton doubled the size of his dwelling after his brother’s death to add rooms for his mother and nieces and nephews. He created a 16-room English-style manor house with a kitchen and service rooms in the basement and a separate combined stable, carriage house, and office. The rebuilt Woodlands Mansion became one of the greatest domestic American architectural achievements of the 18th century, recognized as a leading example of English taste and presaging architectural trends in the following century. As he was improving the residence, Hamilton also redesigned and embellished the grounds in the so-called “English manner” with “invisible” subterranean passages for staff between buildings. For the landscape, he relied, in large measure, on the exchange of novel plant material to provide horticultural interest and distinction to his property. At the same time, an existing greenhouse was expanded extensively. Archaeological explorations of this site, initiated in the first decade of the 21st century, have helped verify the greenhouse location and explain some of Hamilton’s water storage systems.

An old, handwritten label on a seed packet.
“Evolvulus from the Island of Princes; Mr. Thouin, W 1802.” This largely complete packet is in William Hamilton’s handwriting. The “W” probably indicates the seed was collected at The Woodlands in 1802. The packet contains seeds from an unidentified species of Evolvulus or dwarf morning-glory.

A blooming periwinkle morning-glory.

An old, handwritten label on a seed packet.
“Erucago monspeliensis Cavs.; Bunias erucago Linn.” This seed packet is labeled in the “X”-writer hand and shows the characteristic crossed “r.” Bunias erucago, crested wartycabbage or corn rocket, is an edible green.

The yellow flowers of a blooming corn rocket.

An old, handwritten label on a seed packet.
“Silene baccifera H R M; Cucubalus bacciferus Linn.” An example of the “H R M” authority in the “X”-writer hand. Silene baccifera is now the accepted binomial for this species.

A green and white Berry catchfly flower.

By the turn of the 19th century, Hamilton’s land holdings reached 600 acres and his residential estate was universally recognized as one of the most aesthetically and botanically sophisticated properties in North America. After a visit to The Woodlands in July 1806, Thomas Jefferson observed that the property was “the only rival which I have known in America to what may be seen in England.” This was high praise indeed from a man steeped in the world of gardens and international horticulture. Hamilton, a graduate of the College of Philadelphia, the predecessor of the University of Pennsylvania, complemented and reinforced his first- hand experiences with an important library of gardening and botanical books. By 1784, his personal library was known to have held at least 60 important botanical works dating from 1530 to 1770. Unfortunately, his library was sold or otherwise dispersed by the family after his death, so we do not know the full extent of
its contents. A few of his books are now owned by the Library Company of Philadelphia.

Supplying Mount Vernon with Plants

A voracious plant collector, Hamilton was also a supplier of plants to other botanical enthusiasts on a scale that at times appears to have been almost commercial. He supplied George Washington with hundreds of plants for Mount Vernon, and he regularly exchanged specimens with such notable botanists as Henry Muhlenberg, William Bartram, Thomas Jefferson, Humphrey Marshall, David Hosack, and André Michaux. His garden served as an open classroom for Benjamin Smith Barton (1766–1815) and students from Penn, where Barton served as Professor of Botany and Materia Medica. Among other important plants, Hamilton is credited with introducing to North America the ginkgo tree (Ginkgo biloba), the Lombardy poplar (Populus nigra ‘Italica’), the Norway maple (Acer platanoides), and the Chinese tree-of-heaven (Ailanthus altissima), which has recently become the favorite host tree for the invasive spotted lanternfly (Lycorma delicatula).

The leaves and seed pods of the invasive tree-of-heaven.
Leaves and ripening seed pods of tree-of-heaven (Ailanthus altissima).

Close up of a group of Ginko leaves.
The unique, fan-shaped leaves of the ginkgo tree (Ginkgo biloba).

The horticultural knowledge of Hamilton and his two closest associates, the Scottish plant collector John Lyon (1765–1818) and the German botanist Frederick Pursh (1774–1820), both of whom were employed by Hamilton to serve as gardeners, made The Woodlands a logical place for the American Philosophical Society (APS) to turn for assistance when experimenting with plants of unusual scientific interest or believed to have valuable potential for public improvement. In 1794, the APS entrusted Hamilton with a shipment of plants sent by the East India Company’s Scottish botanist and surgeon William Roxburgh (1751–1815). Later, between 1805 and 1807, Thomas Jefferson and the APS gave Hamilton shipments of seeds and cuttings made by Lewis and Clark. One of the best-known plants from that expedition to be propagated at The Woodlands was the Osage orange (Maclura pomifera). Pursh, after leaving his employ with Hamilton and moving to England, published the first descriptions of the plants discovered by Lewis and Clark in his landmark book Flora Americae Septentrionalis (1814).

In 1809, Joseph Dennie (1768–1812), the editor of Port Folio, then the most important political and literary journal in the United States, wrote that Hamilton’s greenhouse and garden contained “nearly ten thousand plants, out of which number may be reckoned between five and six thousand different species, procured at much trouble and expense, from many remote parts of the globe, from South America, the Cape of Good Hope, the Brazils, Botany Bay, Japan, the East and West Indies, &c. &c. This collection,” he continued, “for the beauty and rich variety of its exotics surpasses any thing of this kind on this continent.”

An old, handwritten label on a seed packet.
“large verrucose Guava, No. 2 10 Mar. 1802”. The collection includes two packets from numbered cultivars of guava or Psidium guajava. This variety must have had warty,
or “verrucose,” fruit.

A guava fruit cut in half and one left whole, with green flesh and pith.

An old, handwritten label on a seed packet.
“Hydrangea quercifolia, [Bar]tram’s travels.” This packet represents very early evidence for garden cultivation of William Bartram’s discovery of oakleaf hydrangea, Hydrangea quercifolia. Bartram named and illustrated the plant in his Travels, Philadelphia: 1791. William Hamilton’s presentation copy of Travels with extra illustrations is preserved at the Morton Arboretum in Lisle, Illinois.

A white hydrangea bloom cluster.

Hamilton’s Seed Packets

While most of the living plants that once flourished in Hamilton’s greenhouses and on his property have since been lost, the seed packets found in his house dating from the time of his greatest horticultural activity give us a rare window into Hamilton’s gardening practices and, by extension, those of his contemporaries on both sides of the Atlantic. The packets are of varying sizes, but most are small and hexagonal (rectangular with pointed ends), made of a single piece of folded, white, hand-made paper measuring approximately 4 x 8 cm when folded. Each has a genus and species name written in ink, often in Hamilton’s own hand. Some cite references (i.e., nomenclatural authority for the scientific names given), but some names refer to the people from whom Hamilton obtained the seeds. Names of individuals include “Michx” or “Michaux” (André Michaux, the French botanist and collector who worked in North America from 1785–1800); “Thouin” (Andre Thouin [1747–1824], the long-time head of the Jardin du Roi or Jardin des Plantes in Paris); “Jacq.” (Nikolaus Joseph von Jacquin [1727–1817], scientist from the Netherlands); “Ortega” (Casimiro Gómez de Ortega [1740–1818], Spanish phy- sician and botanist); “Lamarck” (Jean-Baptiste Antoine Pierre Monet, chevalier de Lamarck [1744–1829], French naturalist); “Cav.” or “Cavs.” (Antonio Jose Cavanilles [1745–1804], a Spanish taxonomic botanist active in Paris); and “Bartram” (William Bartram [1739–1823], artist, author, and son of John Bartram [1699–1777]. Both Bartrams were renowned American naturalists whose former home and botanical garden lies just down the Schuylkill from The Woodlands). A few of the packets have place names (“Mexico,” “Cape of Good Hope,” etc.) and some bear dates (1791, 1802, 1803)

An old, handwritten label on a seed packet.
“Hydrangea mutabilis; a most beau[tifu]l flowerd Shrub fro[m Chin]a.” Although a large portion of the label is gnawed away, it is possible to reconstruct what is missing. When he saw it at The Woodlands in July 1800, William Bartram described the blue hydrangea, Hydrangea mutabilis (now H. macrophylla), as “the most beautifull Hydrangia from china,” in a letter to Benjamin Smith Barton.

A blue hydrangea bloom cluster.

An old, handwritten label on a seed packet.
“Eschinom: inundata; with articulated pods; viscid[ula …]s Mic[haux]; by George from Jersey 1803.” In this case Hamilton indicated the collector, probably George Hilton, his long-time gardener, and a location, probably southern New Jersey. Aeschynomene virginica, sensitive jointvetch, was once found on the lower Schuylkill in Philadelphia. It is still preserved in fresh-water tidal marshes in southern New Jersey.

Three yellow sensitive jointvetch blooms.

In 2005, The Woodlands’ seed packets were placed on permanent loan to the Botany Department of the Academy of Natural Sciences of Philadelphia (now part of Drexel University) for storage in their herbarium. Some additional packets and packet fragments discovered later in the same attic area were also deposited in the Academy’s herbarium in 2007. There they are kept with the Academy’s 1.5 million pressed plant specimens from around the world.

Interestingly, more than 100 seed packets collected and packaged in a very similar way by Hamilton’s friend André Michaux between 1785 and 1787 reside in the Academy’s herbarium. Michaux sent them to the APS and they were later deposited at the Academy. A similar set of seed packets from the early 19th century is in the collection at The Royal Botanic Gardens at Kew. The contents of some of these have been found to be viable more than 200 years after they were collected. Whether or not an attempt should be made to germinate some of The Woodlands’ seeds is still under discussion.

How to Germinate 200-year-old Seeds

According to information on the Kew Gardens website, in 2018 scientists at Kew tried to germinate seeds that were over 200 years old and had been found in a leather wallet, with notes indicating that they had come from the Cape Region of South Africa. Germination tests included treating the seeds with liquid smoke to replicate the wildfires which enable seed germination in several species from the region.

They had initial success with three species, labelled as: “Liparia villosa,” “Protea conocarpa,” and an “unknown Mimosa.” Using the International Plant Names Index, scientists traced their likely modern botanical names to identify the plants. They found that “Protea conocarpa” was in fact a Leucospermum. Out of eight Leucospermum seeds, only one germinated—the one that survives today.

Once germinated, the plants were grown in pots. Only the “unknown Mimosa” (an Acacia), and the Leucospermum survived to maturity. Scientists were then able to identify it as a Leucospermum conocarpodendron subsp. conocarpodendron. Since then, the plant has grown significantly and is still flourishing.

a drawing of three plant species respective blooms and leaves.
Arabella Elizabeth Roupell (1817–1914) created this early etching of Leucospermum conocarpodendron (left) and two Protea species. Leucospermum seeds were germinated after 200 years by Kew Gardens. Photo from Wikipedia. Public domain.


An inventory of The Woodlands’ packets has been prepared by Joel T. Fry, curator at Bartram’s Garden, in association with the Botany Department of the Academy of Natural Sciences. For further information on the seed packets, please contact the Botany Department of the Academy of Natural Sciences.

Robert McCracken Peck is Senior Fellow at the Academy of Natural Sciences of Drexel University. His most recent book is Specimens of Hair: The Curious Collection of Peter A. Browne (Blast Books, 2018, with photographs by Rosamond Purcell).

Cite This Article

Peck, Robert McCracken. "A Lucky Find." Expedition Magazine 62, no. 3 (September, 2020): -. Accessed April 17, 2024. https://www.penn.museum/sites/expedition/a-lucky-find/

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