O’odham ancestors domesticated and dry-farmed newly described agave species on a vast scale

Phoenix and Tucson, Ariz. Scientists at Desert Botanical Garden and Archaeology Southwest recently published their discovery of a domesticated species of agave growing in ancient farm fields in southern Arizona’s San Pedro River valley. In the journal Systematic Botany, Wendy Hodgson and Andrew Salywon (Desert Botanical Garden) and William Doelle (Archaeology Southwest) describe the once-prolific crop, which they have named Agave sanpedroensis, as well as the archaeological evidence of its cultivation by ancient farmers of the Sonoran Desert, whom archaeologists associate with the Hohokam archaeological culture.

“The discovery of Agave sanpedroensis is significant because it provides living proof, backed by archaeological evidence, that the Hohokam were growing agaves on a large scale,” says lead author and research botanist Wendy Hodgson. “Although it is not surprising that farmers were growing them near their settlements, the scale at which people transformed the landscape to grow these plants by placing available rocks into piles and linear terraces is really impressive.”

Beginning in the late 1990s, archaeologists with Archaeology Southwest started documenting ancient dry-farming fields scattered across 60 miles overlooking the San Pedro River floodplain. In addition to aggregated rock features, archaeologists found tabular stone knives people would have used to harvest and process the agaves, which they used for food, fiber, medicine, and beverages. The cairns would have served as mulch and protection for the vegetative offsets farmers placed in them. These offsets were ‘pup’ plants from the parent plant’s rhizome, or underground stem.

“We know of Agave sanpedroensis from 12 localities and about 200 surviving plants—it is very rare,” says Hodgson. “The plant seems to reproduce solely by vegetative offsets and not seed, and we don’t know of a wild plant that looks similar. This leads us to hypothesize that it was a domesticated crop.” Domesticated plants result from human selection for certain traits, and are reliant on humans for their cultivation.

Co-author and research botanist Andrew Salywon added, “Because it doesn’t produce seed, this agave lacks the ability to replenish populations that perish through drought and being eaten by animals. These surviving plants are clones growing in the very same fields where farmers planted them more than 600 years ago. This is an opportunity to bring this crop back from the brink of extinction and learn more about the Hohokam economy.”

Archaeologist Bill Doelle agrees that the human side of the plant’s story is significant. “Archaeologists have long written about the so-called collapse of Hohokam population in the 1300s and 1400s,” he said. “This resilient agave species embodies an important counter-narrative: The ancestors of today’s O’odham people found ways to survive under dramatically changed conditions. Unlike genetically constrained agaves, though, the culturally resilient O’odham have adapted and are thriving.”

About Desert Botanical Garden

Desert Botanical Garden is home to one of the world’s most spectacular living collections of desert plants. The Garden’s living collections includes more than 4,000 species and nearly 27,000 individual plants for which scientific records are kept. In addition to providing a stunning display, these plants provide scientists from all over the world with information and material for various research projects. The Garden’s collection of agaves, yuccas and their close relatives is designated a National Collection by the Plant Collections Network. Within this collection are more than 2,000 plants of wild origin representing nearly 350 different species. To learn more about Desert Botanical Garden and the work they are doing to conserve desert plants, visit http://www.dbg.org.

About Archaeology Southwest

Archaeology Southwest is a private 501(c)(3) nonprofit organization based in Tucson, Arizona, that explores and protects the places of our past across the American Southwest and Mexican Northwest. For three decades, Archaeology Southwest has fostered meaningful connections to the past and respectfully safeguarded its irreplaceable resources. Learn more at http://www.archaeologysouthwest.org.   back...