This is the first in a series of occasional posts on interesting or unusual material encountered in the process of sorting and identifying archaeological plant samples. It’s a lot like an archaeological field blog, except that the “field” is the tiny field-of-view under the microscope.
Burned squash (Cucurbita pepo) flower scars from an archaeological site in East Texas. Scale in mm. All photos by Leslie Bush.
The round objects in the photo are squash flower scars from a site in Panola County, Texas, where the ancestors of Caddo Indians lived during the fifteenth through early seventeenth centuries. The excavations were carried out by VersarGMI and funded by the Texas Department of Transportation, whom has graciously provided permission to share the find on CRHR:ARCHAEOLOGY prior to formal publication.
These small black flower scars were preserved through carbonization in an ancient campfire, probably deliberately discarded into the fire as a part of the plant that would not be good to eat. “Flower scars” are small hard tips at the end of fruits in the botanical genus Cucurbita and the Cucurbitaceae, the family that includes squashes, gourds and melons. Flower scars are sometimes called “tori” (singular, “torus”) in reference to their doughnut-like shape. In botanical terminology, squash flowers have inferior ovaries, which means that the fruit develops below the flower. As the fruit matures, the flower dries up and falls off, leaving a circular scar at the top of the fruit where the flower was once attached. Flower scars aren’t terrifically common on archaeological sites, but they’re not rare either. The flower scars are tough enough to survive in the soil after they’ve been carbonized. The rest of the squash rind, although occasionally found on archaeological sites, is often too thin and fragile to survive even if it happens to become carbonized.
A quick tour of the produce section at your local grocery story should turn up several examples of flower scars similar to the ones in the photo. At my grocery store, the closest match is to the scars of acorn squash – which is no coincidence since genetic studies by Deena Decker-Walters and others suggest that acorn-type squashes are part of a Cucurbito pepo lineage that was domesticated in the Eastern United States. (The pumpkin lineage belongs to the same species, but it was domesticated in Mexico.) By the time Caddo ancestors were living at the Panola County site, at least one other species of squash was being grown in the eastern United States (cushaw squash, Cucurbita argyrosperma, domesticated in Mexico), so other kinds of flower scars may also appear on East Texas archaeological sites.
Flower scars of acorn squash (eastern lineage of C. pepo), spaghetti squash (C. pepo var. fastigata), and butternut squash (C. moschata).
Cucurbita squashes are some of the earliest crops known in the Americas. Squashes are the fleshy-rinded descendants of wild gourds, in much the same way that domestic dogs are descendants of wolves: They’ve been bred to have traits that are more desirable for humans. It’s not clear exactly which species or subspecies of Cucurbita is the ancestor of the many modern Cucurbita pepo squash varieties we’re familiar with today. These include crooknecks, straightnecks, cocozelles, scallops, zucchinis, acorn squashes, and pumpkins. We do know that mature wild gourds in the genus Curcurbita have thin, hard shells, and their seeds are often edible but bitter. The tender, immature fruits can be eaten, too. Zucchinis are an example of a C. pepo squash we eat in immature form today.
Thousands of years ago, Native Americans planted the seeds of wild gourds for the immature fruits or the edible seeds. They selected the seeds of thicker-rinded, more succulent gourds for planting, so that over time the gourds became the squashes we know today. Archaeologists use “King’s Rule “ of 2 mm rind thickness to determine whether a rind is thick enough to count as a domesticated squash and not a wild gourd. Rinds thicker than 2 mm begin to appear on archaeological sites in the eastern United States around 3,000 years ago, but the actual growing of gourds would have started much earlier. Archaeologists have found some evidence of this in the form of a 5,700-year-old burned squash rind in central Maine, outside the natural range of wild gourds.
Native American gardeners selected other gourds for planting based on their hard, water-proof shells, resulting in domesticated ornamental gourds that also belong to the species Cucurbita pepo. Even while Native Americans were planting gourds and squashes in their gardens, wild gourds continued to grown on their own, which is why we still see them along roadsides and in preserves today.
A wild buffalo gourd (Cucurbita foetidissima, also called Missouri gourd or stinking gourd), Austin Texas, August 2009. Genetic studies point to other wild gourds such as the Ozark gourd, the Texas gourd, and/or a Mexican wild gourd as the most likely ancestors of modern C. pepo squashes and gourds.
One last point: The wild gourds that became domesticated squashes are not the same as bottle gourds, also called birdhouse gourds or rattle gourds. Bottle gourds belong to a different genus (Lagenaria) within the same botanical family, Cucurbitaceae. Bottle gourds have such a long and interesting history in the Americas that they deserve an entire post all their own. There’s also a tree gourd, sometimes called a calabash, that is a member of the Bignonia family. It isn’t known in Texas prior to the wreck of the French ship La Belle in 1686.
About the Author
Dr. Leslie L. Bush is a CRHR Research Affiliate, and the proprietor of Macrobotanical Analysis.
***Start looking forward to Thursday, and a post by Dr. Jon C. Lohse on the topic of radiocarbon***